[Why do so] many fundamentalists spend so much time in Leviticus and so little time in the New Testament, and I think that’s a remarkably cogent question. Indeed, it is so cogent that I would like to make the suggestion that there is an entire class of self-identified “Christians” who are not Christian at all, in the sense that they don’t follow the actual teachings of Christ in any meaningful way. Rather these people nod toward Christ in a cursory fashion on their way to spend time in the bloodier books of the Bible (which tend to be found in the Old Testament), using the text selectively as a support for their own hates and prejudices, using the Bible as a cudgel rather than a door. That being the case, I suggest we stop calling these people Christians and start calling them something that befits their faith, inclinations and enthusiasms.
I say we call them Leviticans, after Leviticus, the third book of the Old Testament, famous for its rules, and also the home of the passages most likely to be thrown out by Leviticans to justify their intolerance (including, in recent days, against gays and lesbians — Leviticus Chapter 18, Verse 22: “Thou shalt not not lie with mankind, as with womankind; it is abomination”).
To suggest that a Christian is actually a Levitican is not to say he or she is false in faith — rather, it is to suggest that their faith is elsewhere in the Bible, in the parts that are easy to understand: The rules, the regulations, all the things that are clear cut about what you can do and what you can’t do to be right with God. Rules are far easier to follow than Christ’s actual path, which needs humility and sacrifice and the ability to forgive, love and cherish even those who you oppose and who oppose and hate you. Any idiot can follow rules; indeed, there’s a good argument to made that idiots can only follow rules. This is why Leviticans love Leviticus (and other pentateuchal and Old Testament books): Chock full of rules. And you can believe in rules. That’s why they’re rules.
Source: Leviticans ~ John Scalzi, Whatever