Based on what scripture?
Those who have studied Revelation extensively understand that John gets much of his figurative language from the OT prophets and (as I'll demonstrate later) certain Roman and Greek mythology as well.
So check out the below passage. Here those with the mark are spared just as in Rev 13.
Eze 9:
And He called to the man clothed with linen, who had the writer’s inkhorn at his side; [SUP]4 [/SUP]and the Lord said to him, “Go through the midst of the city, through the midst of Jerusalem, and put a mark on the foreheads of the men who sigh and cry over all the abominations that are done within it.” [SUP]5 [/SUP]To the others He said in my hearing, “Go after him through the city and kill; do not let your eye spare, nor have any pity. [SUP]6 [/SUP]Utterly slay old and young men, maidens and little children and women; but do not come near anyone on whom is the mark; and begin at My sanctuary.”
So, in Rev 13 you have two groups living together, those "marked" and those "not marked." Those marked in Rev 13 as in Eze 9 are spared while those without the mark are killed. Then later in Rev 14 we see those who are marked are divinely punished.