The blindness of the unbelievers to the power and might of Allah; the denial of the fact that it is just as easy for Allah to create us as it is for Him to resurrect us with His command "Be" and it becomes 34:7-9
34:7 The unbelievers say, 'Shall we direct you to a man who will tell you that when you have been utterly torn into pieces you will be raised in a new creation?
34:8 What, has he forged a lie about Allah, or is he mad!' No, those who do not believe in the Everlasting Life are in the punishment and in far error.
34:9 Have they not seen what is before them and behind them in heaven and earth? If We willed, We would make the earth swallow them up, or We would let lumps from heaven fall down on them. Surely, there is a sign in this for every penitent worshiper.