What Does the Crucifixion Mean?

After the movie, i've been forced to ask myself what does the crucifixion mean? And to me, it means, if you crucify others, you crucify yourself. The ultimate meaning of the cross is that god so loved the world he gave his only begotten son, christ, to die on that cross to pay our sin debt in full for ever. Only perfect god, perfect man could do that. Wetl he's the part i don't understand. How could, how could jesus have died for all men's sins for all time,. when such evil exists thatdoes that exonerate them?