It's right there in the bible... god does not mince words...
If a man has sexual intercourse with a male as one has sexual intercourse with a woman, the two of them have committed an abomination. They must be put to death; their blood guilt is on themselves.
Pretty straight-forward, right?
"They must be put to death"... you must murder them... will you do it?
I wouldn't do it for two reasons. One, is that I don't want to be in jail for killing another person , homo or not. Two, is I believe in another saying in the bible that "thou shalt not kill". God is the one who will punish those who have made a mistake and those who did not follow him. The command stated on leviticus 20:13 is only valid at the time of Jesus I believe from when he can talk to God.