The Advantages of Sincerity Over Self-Deception

Throughout eternity a person is tested only once and this period of testing is made up, on average, of six or seven decades. A person's behavior during this testing period determines the form of his eternal life. If someone spends this brief but extremely important period in self-deception, he fails the test. The truth is this: By deceiving himself, a person can neither change the truth nor evade his responsibility. On the contrary, running away from the truth works only against the person himself. At every moment when he silences his conscience and tries to comfort himself with all kinds of illusory excuses and rationalizations, he is really suffering a terrible loss. Unless Allah wills it, the return for this lack of intelligence will be a sorrow which can never be relieved.
Since this is the case, there is no need for self-deception. It is sufficient to carry out one's duty of serving Allah with very clear knowledge and care. This is possible if the person heeds the voice of his conscience and conforms to Allah's Book. For a sincere believer, there is no other way. The finest and most beneficial way for a person is to be constantly aware that each moment brings him a little closer to death and the Day of Judgment, and that every act and every thought which crosses his mind is known to Allah.
Know that this is the way which leads to sincerity towards Allah and that it is actually the simplest. After a little thought and a clear decision, a person can live his entire life in the clarity of knowledge which that decision brings. Once he gains this clarity of knowledge, it will not allow him to do himself any serious damage by deceiving himself.
Do not forget that deceiving yourself is like playing with fire. While a person is enjoying himself and devoting himself wholly to worldly things, he may at any moment find angels at his side who have come to take his life. Will he be able to continue the same game and the same deception when the angels, as a verse of the Qur'an has it, "pluck out harshly"?
Will he be able to say, "How well I have done. Throughout my life in the world I have eaten, drunk, traveled, enjoyed myself and ignored my responsibilities and my duty of obedience"? Of course not. This is an idea which would not occur even to the most heedless person. On the contrary, at that moment he will experience indescribable panic and terror, and that is just the beginning. When he enters the gates of Hell this terror and remorse will be unbearable, and he will suffer eternal torment.
This is a truth which should not be neglected even for only a moment. Allah points this out in the Qur'an and describes the remorse and helplessness of the ones who deceive themselves as follows:

Turn to your Lord and submit to Him before punishment comes upon you, for then you cannot be helped. Follow the best that has been sent down to you from your Lord before the punishment comes upon you suddenly when you are not expecting it; lest anyone should say, "Alas for me for neglecting what Allah was due, and being one of the scoffers!" or lest they should say, "If only Allah had guided me, I would have had fear of Allah," or lest he should say, when he sees the punishment, "If only I could have another chance so that I could be a good-doer!" (Surat az-Zumar: 54-58)