This objection stems from an oversight of the fact that the main branch of perfection is voluntary perfection. In other words, perfection (and development) means that man traverses the path using his own feet and by means of his resolve. If he were to be held by the hand and taken by force, neither would it be a matter of glory nor would real perfection be achieved.
For example, if a person out of his own will decided to give one riyal from his wealth in charity, he would have progressed towards moral perfection in that same ratio, whereas if millions were to be taken forcefully from him and given in charity, he would not have advanced even one step towards this goal. It is for this reason that in various verses of the Qur’an this reality has been asserted that had Allah (s.w.t.) desired, all the people would have become believers, under compulsion. However such faith would not have proved beneficial to them.1
وَلَوْ شَاءَ رَبُّكَ لَآمَنَ مَنْ فِي الْأَرْضِ كُلُّهُمْ جَمِيعًا
“And if your Lord had pleased, surely all those who are in the Earth would have believed - all of them.”2