[It is] so He will make clear to them [the truth of] (16:39)

Almuntakhab Fi Tafsir Alquran Alkarim

It is an act of mercy to both the guilty and the innocent- that Allah resurrects the dead and restores them to life to illucidate to them the strained points upon which the whole unreasoning turned and the points which were once in the heat of. dispute so that the infidels who denied Him and/or His statutes realize how unjust they were to themselves and to others to justify their falsehood and assert it as true

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(16:39) And It must be fulfilled so that He may reveal to them that thing about which thay are differing, and that the disbelievers might know that they were liars. *35

[It is] so He will make clear to them [the truth of] meaning

*35) n v. 39 those two things have been stated which rationally and morally require that there must be Resurrection and Life-after-death, that is: (1) to reveal what the reality was, and (2) to reward or punish people in accordance with the right or wrong stand they took about it in this world. It is common knowledge that since the creation of Man on the Earth there have been many differences regarding the Reality which have been sowing dissension between families, nations and races. These have also led to the formation of many different societies, cultures and creeds on different theories. In every age millions of the torch-bearers of each of these theories have been putting at stake their all-life, property, honour-to propagate and defend their favourite theory. Nay, there has aIways been such a bitter conflict between them that each group tried to annihilate the other, who, in his turn, stuck to it to the last. This being the case, common sense demands that such far-reaching and serious differences should be cleared some time or other, so as to decide with certainty what was right and what was wrong, who was in the right and who was in the wrong. Obviously, it is not possible to lift the curtain from the Reality in this world so as to reveal things in their true perspective. This is because the system on which this world has been created does not allow this. Therefore, there should be another world to fulfil this demand of common sense.
This is not the demand of common sense alone but also of the moral sense, which requires that the partners in this conflict should be rewarded or punished according to right or wrong, just or unjust part they played in it. For, some of these committed cruelties on the others, who had to make sacrifices for their cause. Then each one should also bear the responsibility for formulating and practising a moral or immoral philosophy which influenced millions and billions of others for better or worse. Moral sense demands that there should be a time for the moral consequences to take their due course. As this is not possible in this world there should be another world for the purpose.
 

[It is] so He will make clear to them [the truth of] meaning in Urdu

اور ایسا ہونا اس لیے ضروری ہے کہ اللہ اِن کے سامنے اُس حقیقت کو کھول دے جس کے بارے میں یہ اختلاف کر رہے ہیں اور منکرین حق کو معلوم ہو جائے کہ وہ جھوٹے تھے