Why are parts of Leviticus used, but other parts ignored?

So you would assert that certain things from the Bible are untrue and not the inerrant Word of God. This would mean that the credibility of the other passages could be called into question, especially given that the oldest transcripts we have for the New Testament books alone are from hundreds of years after the originals, and they vary widely amongst each other.

Because of this, one could argue that the parts of the Bible that condone slavery, the rape of children (as long as it's male on female), and even the parts that may be interpreted as being anti-homosexual, could also be, as you said, "that man has added this betrayal to the word of God."

It's troublesome, because as many of these things are widely accepted in the Bible--and compounded by corruption as it was copied over the millenia, as well as what is lost in translation (or mistranslation)--it would be near impossible for even devout Christians to confirm what might be true. Every single person would basically have to learn Greek and Hebrew for themselves and personally compare the old transcripts to figure out what's what. Otherwise, you could just trust the experts to figure it out and read their own translation of their interpretation of what the original might have been.

One way or the other, this viewpoint would tend to undermine the fundamentalist belief that everything in the Bible must be taken as the literal and inerrant Word of God, which means that we should be able to interpret it as we will, throwing out the parts that seem to us not to fit with the message and keeping those parts that do.

So you say that because homosexual relationships would not naturally produce offspring, this is proof that it is wrong. The premise that doing things that would not, if universally practiced, result in the continuation of the human species can be considered wrong and sinful unfortunately leads to other problems.

What would you say about those who choose to be chaste for the rest of their lives, such as Catholic priests or monks or nuns? Would they be considered sinning because if everyone was chaste the population would not be sustainable? I recall that there is a passage in the Bible which discusses marriage and, in a roundabout fashion, procreation. Jesus says that it is good to marry, but it would be better to be like Jesus (which is interpreted as not marrying or having children). Jesus, himself, is believed to have remained chaste. If everyone were to act like Jesus, the population would also be unable to sustain its numbers.

Would you also say that any use of contraceptives would be sinful? I know there are some sects of Christianity that would say it is, but it seems strange that it would be so, even in the context of marriage. Some people make the mistake that any time you're having sex all it is is carnal lust. To those in loving relationships, you know this not to be true. Sexual intercourse is one of those things that helps to affirm the emotional and spiritual connection between you and your spouse. Why should one necessarily have to be trying for children every time one desires closeness with one's spouse?

It also may bring into question those with certain diseases, genetic or otherwise, that might prevent them from having children. Are these people who simply choose not to have children sinful for not doing so, even when they may be unable to physically or because they might put their potential children at risk by having them?

So, you see, these issues alone hopefully elucidate the reason creating a universal out of an incidental is a poor way to prove it wrong. The fact is that in any given population at any given time, about 10% of it will be homosexual. The other 90% have no problem continuing the human species, and it would be vastly unlikely that we would ever have a situation which would leave us with only homosexuals to repopulate the planet. If that was the case, I'm sure that if it was the human race at stake, they might be willing to consider heterosexual intercourse, even though they wouldn't like it. Anyway, the fact that homosexuality is also been present in most animal species seems to confirm that this is indeed normal behavior and apparently not harmful to the species.