( فَإِن كَذَّبُوكَ) (So if they deny you, [O Muhammad],): This is addressed to the Prophet Mohammad (saws).

(فَقُل رَّبُّكُمْ ذُو رَحْمَةٍ وَاسِعَةٍ ) (say, “Your Lord is the possessor of vast mercy;): It does not say (is of severe punishment) but rather: (is the possessor of vast mercy). However, we should beware of constant mercy, for it is only a mercy of deferment.

(وَلَا يُرَدُّ بَأْسُهُ عَنِ الْقَوْمِ الْمُجْرِمِينَ) (but His punishment cannot be repelled from the people who are criminals): Allah’s (swt) punishment surely is coming and criminals will not be able to escape from it.