Do you just wave it in her face and threaten to hit her? What if she still doesn't comply. Sorry, but instructions to beat your wife are found in the Koran. I think a better way of looking at it is how you first approached it:
the Bible also mentions beating women and slaves. I'm sure modern Christians don't believe in it, so why should we hold up muslims to the same standard?Why? Because many Muslims still beat their wives, and few Christians (at least in America) do. Let's say in order for a Muslim nation to be considered "civilized" they have to have outlawed wife-beating, and let's hold Christian nations to the same standard. Now, count how many civilized Christian nations there are against how many civilized Muslim nations...
Where does the Bible mention beating women? Can you provide a cite?