Easy, as a Christian I believe the whole Bible as Gods word. Leviticus says that homosexuality is a sin punishable by death. Jesus spoke against all sin including sexual immorality which homosexuality is. Saying Jesus never spoke against homosexuality is a lame excuse to defend the sick sin of gay. Gay is SICK>
I think it's foolish and counterproductive to say you believe every word of the Bible literally. Because your opponents will manipulate that statement to mean all of the Bible can be rendered into not eating pork products...'silly'.
A distinction is needed between old outdated laws and customs, venial sins of that sort and the clear and distinct mortal sins that come with the direst of warnings. Jude 1 contains such a mandate against a culture of homosexuality taking over...most particularly a warning to those 'faithful' who stand by and do nothing as it happens. The Pit of Fire awaits those who do nothing to "earnestly contend" for the "common salvation"..
I didn't write the book, but I think I know the reasoning behind why it is so adamant about that one point on homosexuality.
If you accept that the world is here to test souls, to temper them and to bring those souls heavenward or hellbound, depending on their performance, blending the matrix these souls are tested in would be among the top ten deadliest sins. And that sin would be tampering with the matrix.
If you talk to liberals about if they support diversity, they instantly say 'yes'. Ask them about cultural diversity across the world and should it be preserved at all costs. They will say "yes, it helps people learn about differences and stimulates growth and change in the observer of a different culture.
Then you ask them if they believe this same theory should be applied to the sexes. ie: should there be different standards for males vs females. Then the answer is "no". Yet males and females are different, it is genetic and their differences cause each other's genderless spirit to grow from a standpoint of observation and interaction with each other.
Gays make the mistake of thinking that because a spirit they like is born in the same gender, they then should have sex with it. This is wrong. For how will spirits of affinity ever learn to just love each other solely as friends? This and many other lessons born from the distinct male/distinct female matrix are dissolved when homosexuality demands to be not just accepted, but eventually as in Sodom, the norm. If you don't believe me that this is the end game, just study Ancient Greece or for a more contemporary admission:
http://www.usmessageboard.com/current-events/341681-white-cis-male-gay-privilege.html
Random sin is bad, like murder, rape etc But to incorporate a mortal sin as a cultural value stands to harm the most people over time than any individual sin ever could dream to do. So this is why I understand Jude 1 and why christians MUST abide. To not do so is to commit the unthinkable crime: tampering with God's plan in the most significant way possible.