Re-engineering the mindsets of people has been termed tazkiyah in the Quran. The mindset of people differs from age to age. In ancient times thinking was traditional. In the modern age, it is scientific. In the traditional age, the word “purification” or ‘reform’ of the self was used. To bring about tazkiyah in people of the present times, it is essential to speak to them in a way that addresses their minds. The modern man can understand tazkiyah if we use the words conditioning and de-conditioning of the minds. Man is born in his nature. As he lives in society, his personality or mind becomes conditioned. Thus, every person is a case for the conditioning of the mind. To purify one’s mind, it is essential to de-condition his mind, i.e., re-engineer it to make him capable of seeing reality “as it is”. There are two significant parts of the human mind, the conscious and the unconscious. It is quite natural for negative feelings to, first of all, enter the conscious part of the mind. If such feelings are not immediately cast out from the mind, they gradually reach the unconscious part of the mind, from where it becomes difficult to eradicate them. Then they become a permanent part of one’s personality. Therefore, man should always remain vigilant about this. At all times, he should keep converting his negativity into positivity. He must de-condition his conditioned mind, re-engineer his mind, purify it, and keep it free from negative influences. The only way to do this is to repeatedly remind himself of death and reflect on the purpose of life in the light of the Quran. Re-engineering the mind, tazkiyah is a continuous process of developing a purified, positive personality that God may find eligible for entry into Paradise.