Everyone can achieve enlightenment, according to the Buddha. The question is whether one has the wish to do it, and has the faith and diligence in the practice of holy life.
The first thing to do is to find refuge in the Buddha, Dhamma and Sangha. The fundamental doctrine is the Four Noble Truths: 1) life is full of suffering, generally. 2) All suffering are due to desire. 3) Suffering stop when desire ceases. 4) The way leading to cessation of desire and suffering is the Noble Eightfold Path. Everyone who practices (not just knowing) walking the Path can achieve enlightenment if he/she strives diligently.
There are 7 types of suffering: birth, aging, illness, death, separated from love one, association with the dislike, not getting what one wants. These are unavoidable in life. The source of the suffering is birth, without which one will not have all other suffering. The cause of birth is karma. One is reborn after death due to karma, which includes the desire to be reborn, i.e. desire for existence. This is the belief in Buddhism. If one is enlightened, he will not think it’s fun to be reborn again and again for an infinite number of cycles to experience the suffering. However, one can’t escape the cycle of Samsara just by praying or wishing, or just by abandoning the desire for existence. To achieve enlightenment and be liberated, feeling satisfied in this life and never being reborn again, one must let go of all attachments. This is so logical; to become truly free, all fetters binding oneself to the world must be broken. Other than desire for existence, one must also abandon desire for nonexistence and desire for sensual pleasure. Killing oneself, having no will to live, is a desire for nonexistence. Thus, suicide and self-torture/asceticism will only lead to bad rebirth as ghost, animal or even in Hell. One must instead walk the middle path, wanting little, be content, not indulge in sensual pleasure, and follow the Noble Eightfold Path to cultivate perfection of virtue, equanimity and wisdom to achieve enlightenment. Having no attachment to rules and rituals, no attachment to views, no attachment to self-identification are also essential. Meditation can help one to have strong concentration to focus inward on his body, feeling, mind, and Dhamma. With no desire, he will have no greed, hatred and delusion, therefore no suffering. Every little victory will give him delight, happiness or equanimity. This is the more superior form of happiness one can have by living a holy life. He will live happily every second of his life until the last second when the body breaks up and is abandoned. The true self is naturally liberated and permanently escapes the cycle of Samsara.
How does one know whether there is afterlife or rebirth after death? If one bets that there is NO afterlife or rebirth after death, what is the risk and profit in this life and the afterlife? If one bets that there is afterlife or rebirth after death, what is the risk and profit in this life and the afterlife? The Buddha gave the answers in Apaṇṇaka Sutta of Majjhima Nikāya as follows:
“Householders, is there any teacher agreeable to you in whom you have acquired faith supported by reasons?”
“No, venerable sir, there is no teacher agreeable to us in whom we have acquired faith supported by reasons.”
“Since, householders, you have not found an agreeable teacher, you may undertake and practise this incontrovertible teaching; for when the incontrovertible teaching is accepted and undertaken, it will lead to your welfare and happiness for a long time.
And what is the incontrovertible teaching?
Householders, there are some recluses and brahmins whose doctrine and view is this:
‘There is nothing given, nothing offered, nothing sacrificed; no fruit or result of good and bad actions; no this world, no other world; no mother, no father; no beings who are reborn spontaneously; no good and virtuous recluses and brahmins in the world who have themselves realized by direct knowledge and declare this world and the other world.’ — Group 1
Now there are some recluses and brahmins whose doctrine is directly opposed to that of those recluses and brahmins, and they say thus:
‘There is what is given and what is offered and what is sacrificed; there is fruit and result of good and bad actions; there is this world and the other world; there is mother and father; there are beings who are reborn spontaneously; there are good and virtuous recluses and brahmins in the world who have themselves realized by direct knowledge and declare this world and the other world.’ — Group 2
What do you think, householders?
Don’t these recluses and brahmins hold doctrines directly opposed to each other?”
“Yes, venerable sir.”
“Now, householders, of those recluses and brahmins whose doctrine and view is this (Group 1):
‘There is nothing given … no good and virtuous recluses and brahmins in the world who have themselves realized by direct knowledge and declare this world and the other world,’ it is to be expected that they will avoid these three wholesome states, namely, good bodily conduct, good verbal conduct, and good mental conduct, and that they will undertake and practise these three unwholesome states, namely, bodily misconduct, verbal misconduct, and mental misconduct.
Why is that?
Because those good recluses and brahmins do not see in unwholesome states the danger, degradation, and defilement, nor do they see in wholesome states the blessing of renunciation, the aspect of cleansing.
Since there actually is another world, one who holds the view ‘there is no other world’ has wrong view, wrong intention, wrong speech, and opposed to those arahants who know the other world.
Since there actually is another world, one who convinces another ‘there is no other world’ convinces him to accept an untrue Dhamma; and because he convinces another to accept an untrue Dhamma, he praises himself and disparages others.
Thus any pure virtue that he formerly had is abandoned and corrupt conduct is substituted.
And this wrong view, wrong intention, wrong speech, opposition to noble ones, convincing another to accept an untrue Dhamma, and self-praise and disparagement of others — these several evil unwholesome states thus come into being with wrong view as their condition.”
“About this a wise man considers thus:
‘If there is no other world, then on the dissolution of the body this good person will have made himself safe enough.
But if there is another world, then on the dissolution of the body, after death, he will reappear in a state of deprivation, in an unhappy destination, in perdition, even in hell.
Now whether or not the word of those good recluses and brahmins is true, let me assume that there is no other world: still this good person is here and now censured by the wise as an immoral person, one of wrong view who holds the doctrine of nihilism.”
“But on the other hand, if there is another world, then this good person has made an unlucky throw on both counts: since he is censured by the wise here and now, and since on the dissolution of the body, after death, he will reappear in a state of deprivation, in an unhappy destination, in perdition, even in hell. He has wrongly accepted and undertaken this incontrovertible teaching in such a way that it extends only to one side and excludes the wholesome alternative.”
(Group 1 has bet on a position which is risky but no profit in return for that risk. They will lose if there is another world, of which their unwholesome karma will lead to rebirth in woeful realm. They will also lose if there is no other world, because their unwholesome deeds will cause them to be censured by the wise as immoral persons.)
“Now, householders, of those recluses and brahmins whose doctrine and view is this (Group 2):
‘There is what is given … there are good and virtuous recluses and brahmins in the world who have themselves realized by direct knowledge and declare this world and the other world,’ it is to be expected that they will avoid these three unwholesome states, namely, bodily misconduct, verbal misconduct, and mental misconduct, and that they will undertake and practise these three wholesome states, namely, good bodily conduct, good verbal conduct, and good mental conduct.
Why is that?
Because those good recluses and brahmins see in unwholesome states the danger, degradation, and defilement, and they see in wholesome states the blessing of renunciation, the aspect of cleansing.
Since there actually is another world, one who holds the view ‘there is another world’ has right view, right intention, right speech, and not opposed to those arahants who know the other world.
Since there actually is another world, one who convinces another ‘there is another world’ convinces him to accept true Dhamma; and because he convinces another to accept true Dhamma, he does not praise himself and disparage others.
Thus any corrupt conduct that he formerly had is abandoned and pure virtue is substituted.
And this right view, right intention, right speech, non-opposition to noble ones, convincing another to accept true Dhamma, and avoidance of self-praise and disparagement of others — these several wholesome states thus come into being with right view as their condition.”
“About this a wise man considers thus:
If there is another world, then on the dissolution of the body, after death, this good person will reappear in a happy destination, even in the heavenly world.
Now whether or not the word of those good recluses and brahmins is true, let me assume that there is no other world: still this good person is here and now praised by the wise as a virtuous person, one with right view who holds the doctrine of affirmation.
And on the other hand, if there is another world, then this good person has made a lucky throw on both counts: since he is praised by the wise here and now, and since on the dissolution of the body, after death, he will reappear in a happy destination, even in the heavenly world.
He has rightly accepted and undertaken this incontrovertible teaching in such a way that it extends to both sides and excludes the unwholesome alternative.”
(Group 2 has bet on a position which will surely bring profit but no risk. They will win if there is another world, of which their wholesome karma will lead to rebirth in happy destinations. They will also win if there is no other world, because their wholesome deeds will cause them to be praised by the wise as moral persons.)
“Householders, there are some recluses and brahmins whose doctrine and view is this:
‘There is definitely no cessation of being.’
Now there are some recluses and brahmins whose doctrine is directly opposed to that of those recluses and brahmins, and they say thus:
‘There definitely is a cessation of being.’
What do you think, householders?
Don’t these recluses and brahmins hold doctrines directly opposed to each other?”
“Yes, venerable sir.”
“About this a wise man considers thus:
‘These good recluses and brahmins hold the doctrine and view “there is definitely no cessation of being,” but that has not been seen by me.
And these other good recluses and brahmins hold the doctrine and view “there definitely is a cessation of being,” but that has not been known by me.
If, without knowing and seeing, I were to take one side and declare:
“Only this is true, anything else is wrong,” that would not be fitting for me.
Now as to the recluses and brahmins who hold the doctrine and view “there definitely is no cessation of being,” if their word is true then it is certainly still possible that I might be reborn as human, ghost, animal or in Hell. (i.e. No good following this view because the outcome is bad whether their word is true or not.)
But as to the recluses and brahmins who hold the doctrine and view “there definitely is a cessation of being,” if their word is true then it is possible that I might here and now attain final Nibbāna. (i.e. Surely good following this view because the outcome is good whether their word is true or not.)
The view of those good recluses and brahmins who hold the doctrine and view “there definitely is no cessation of being” is close to lust, close to bondage, close to delighting, close to holding, close to clinging; but the view of those good recluses and brahmins who hold the doctrine and view “there definitely is cessation of being” is close to non-lust, close to non-bondage, close to non-delighting, close to non-holding, close to non-clinging.’
After reflecting thus, he practises the way to disenchantment with being, to the fading away and cessation of being.”
(One loses nothing by following the Noble Eightfold Path.)
“Here, householders, a Tathāgata appears in the world. He understands:
‘Birth is destroyed, the holy life has been lived, what had to be done has been done, there is no more coming to any state of being.’
This, householders, is called the kind of person who does not torment himself or pursue the practice of torturing himself and who does not torment others or pursue the practice of torturing others — the one who, since he torments neither himself nor others, is here and now hungerless, extinguished, and cooled, and abides experiencing bliss, having himself become holy.”
When this was said, the brahmin householders of Sālā said to the Blessed One:
“Magnificent, Master Gotama! Magnificent, Master Gotama! Master Gotama has made the Dhamma clear in many ways, as though he were turning upright what had been overthrown, revealing what was hidden, showing the way to one who was lost, or holding up a lamp in the darkness for those with eyesight to see forms.
We go to Master Gotama for refuge and to the Dhamma and to the Saṅgha of bhikkhus. From today let Master Gotama accept us as lay followers who have gone to him for refuge for life.”