Christians, why did God command us to be circumcised in the old testiment? Gal. 4:4?

I was always told it had to do with obedience even though I don't believe that. Many people just don't like the sight of it despite the importance of it to a man (yes including sexually). Now we have all these idiots going around having their children circumcised. The child doesn't even get a say in the matter.