I'm a little on the fence on the question of dressing up for church. I was raised that you wore a dress (girls) and slacks (boys), there was no wearing of shorts unless they were
"dressy". We had our "Church Clothes/Sunday Best" and they weren't worn to play in, they were for church. It seems though these days the rules are much more relaxed and pretty much as long as you show up it doesn't matter what you wear to church. I've even seen tank tops and flip flops being worn. I believe that as long as you are there to receive God's message he probably doesn't mind your dress code. However, I also think that you should at least put a little effort into it and try to dress with a little decorum.