There are many arguments for the traditional Christian position that homosexual activity is sinful, the best of which don't rely on Levitical passages. This passage, from the Roman Catholic office "Congregation for the Doctrine of the Faith", gives a pretty good argument against state sponsorship of gay marriage.
http://www.vatican.va/roman_curia/co...unions_en.html. It's worth checking out for your topic.
Lebell is right; the concept of the afterlife among ancient Hebrews seems to have been comparable to the Greek conception of Hades -- a sort of half-life of shadows. By the time of Christ, there seems to have been some argument regarding the resurrection of the dead, but I don't know when this concept enters the Jewish mythos.