Concise Bible Dictionary:

The wrath of God against all ungodliness and unrighteousness of men is plainly declared in scripture, and will surely fall upon the children of disobedience (Rom. 1:18; Col. 3:6). The fierceness of that wrath is spoken of (Rev. 16:19). How vain then for the false teachers to speak only of the love of God, and to say that because “God is love” there will be mercy for all eventually. There is grace for all now, but there is as surely a day of wrath coming, for God is righteous.