Revelations 16:15 meaning / open debate

Christ wil come back as a thief ..what does that mean ? what does it mean .. lest he walk naked ? and they see his shame ?
Revelations 16:16 And he gathered them together into a place called in Hebrew tongue Armageddon . As per Britannica's definition . A place where the kings of the earth under demonic leadership will wage war on the forces of Godat the end of history.