Critics have been known to argue that rather than being rules against homosexuality, passages like those in Leviticus 18 are not against gay sex per se, but against 'sex with boys' and that it was also prohibited because the male 'seed' was so valuable... The laws of the OT can be broken down into three categories: First, universal moral laws. Second, cultural universals (laws geared to Israel's culture that have a universal moral law behind them). Finally, ceremonial laws.

Are the Leviticus passages in the first category or the second? They are in the first category for the following reasons:
1. Note first the CONTEXT... Both are set in the middle of other laws regarding sexual behavior: Don't lay with your mom, your aunt, etc. The context of the commands is that of Category 1 laws: Universal absolutes. The punishments range from 'worst to best', from death to expulsion to barrenness. The context, the structure of the commands, and the punishment together suggest that what we have here is a universal condemnation of all such behavior.
2. The inclusion of Molech here is an incidental; the homosexual element is shown as (yet another) reason why worship of Molech is wrong.
3. The Jews NEVER interpreted these verses in any way other than against plain old homosexual behavior. They never saw any kind of 'culture factor' behind this prohibition.
4. There are very SPECIFIC condemnations of temple prostitution elsewhere (Deut. 23:17-8). This would suggest that the Lev. cites are not 'roundabouts' or allusions to that practice.