﴿ وَقَالَ ٱلَّذِينَ كَفَرُوا۟ لَوْلَا نُزِّلَ عَلَيْهِ ٱلْقُرْءَانُ جُمْلَةًۭ وَٰحِدَةًۭ ۚ كَذَٰلِكَ لِنُثَبِّتَ بِهِۦ فُؤَادَكَ ۖ وَرَتَّلْنَٰهُ تَرْتِيلًۭا ﴾

“Now they who are bent on denying the truth are wont to ask. “Why has not the Qur’an been bestowed on him from on high in one single re­velation?” [it has been revealed] in this manner so that We might strengthen thy heart thereby - for We have so arranged its component parts that they form one consistent whole -”

When the Quran was revealed, it was not revealed all at once, but part by part over a period of 23 years. Those who denied the truth made this an excuse to say that this was a man-made book and not the book of God, because it would not have been difficult for God to prepare the whole book at one time. It was clarified that the Quran was not simply the work of any author. It was a divine proclamation of the Truth. One of the strategies of preaching God’s will is that it is presented to people gradually, so that it progressively takes root in society. Every objection against such activity—which is based on perfect Truth—is a false one. Whenever such an objection is raised, but then is properly clarified, the authenticity of the preacher’s call is reinforced; it is never in doubt at any stage.