As far as God goes, those that claim they know why He does everthing He does are the most dangerous people on earth IMO. Why? Because they can get new and naive believers to do whatever they want. I will never claim to know everything.
Sometimes we follow the rules without fully understanding the reason the rule is in place. We do it everyday in society. I don't understand why you have such a hard time understanding a Christian doing the same. Maybe it's more that you don't want to understand.