Unbelievers love to bring forth unreasonable commands from the Bible to prove that it’s wrong. Leviticus 19:19 is one of their favorites:
“You shall keep my statutes. You shall not let your cattle breed with a different kind. You shall not sow your field with two kinds of seed, nor shall you wear a garment of cloth made of two kinds of material.
Now, that certainly seems odd, doesn’t it? But Jonathan Morrow explains it all clearly enough in Think Christianly. On page 166 he quotes Gordon Fee and Douglas Stuart:
These and other prohibitions were designed to forbid the Israelites to engage in fertility cult practices of the Canaanites. The Canaanites believed in sympathetic magic, the idea that symbolic actions can influence the gods and nature…. Mixing animal breeds, seeds, or materials was thought to “marry” them” so as magically to produce “offspring,” that is, agricultural bounty in the future.
I had never heard that before. Had you? Naturally I wondered whether it was something I could count on. Are Fee and Stuart right? Is this true?
I didn’t know. That makes rather a weak position to hold then, doesn’t it?
Maybe not. Let’s think about this. Do you know whether Fee and Stuart are right? Answer quick now, and do it on your own — no googling allowed!
You wanted to look it up, didn’t you? That means you didn’t know it was wrong. You didn’t know it was right, either, but that’s surprisingly irrelevant.
Suppose you did look it up and found it false. The very fact that you had to look it up shows that the “unreasonable command” objection fails. In order for the objection to stand, we have to know with pretty firm confidence that the command is unreasonable. If you wanted to look it up on Google, that means you don’t have the firm confidence you need to have, in order to raise the objection.
Now, there are some biblical commands that aren’t so culture- and context-dependent. We can recognize them by how frequently and in how many different contexts they are presented, and by the strength of their connection to identifiable culture-transcending principles. By those tests, Leviticus 19:19 is clearly tied to one time and one place, unlike commands relating to (for example) love for God and neighbor, honesty, integrity, and sexual behavior.
As far as I’ve been able to determine from my studies, Gordon and Fee’s answer is reliable. It’s a good answer. The point I hope you’ll catch here, though, is that it almost doesn’t matter if it’s the right answer, because it’s a good enough answer to illustrate the fact that when atheists and SSM advocates laugh at Lev. 19:19 and other culture-dependent commands, they’re laughing in ignorance. They don’t know what they’re laughing over. Thy don’t know the culture they’re denigrating; and either they don’t know that they don’t know, or else they don’t care that they don’t know.
And this also means that when someone says Christian belief is irrational because it includes commands like this one, they’re showing how little they know, too.
See more on this from Tim McGrew here and following.