Funny you posted this...I started a bible study this week and they had child care for those of us with kids - and they are actually doing a mini-lesson with the kids each week we are there....except for VBS week.  I brought my boys with the expectation that they would learn something new about God's word.  It's not a one week process, just as my spiritual growth is not a one week miracle.  It all starts by the examples set at home and what they see around them.  

I think that VBS is a great tool to grow in a particular spot - just like a bible study.  However, there is no replacing regular church attendance and parents modeling what was talked about in VBS, Sunday school, and living how we expect our children to live, treat others....I think you get the idea.     

I've been a VBS volunteer many times so I've thought about these things even though mine is still on the way. I think it is a great way to get kids introduced to church as more of an outreach event. I also think it can just be a lot of fun for the kids and a great way for them to socialize with other kids their age for a week since they aren't in school. I don't think it should be used as "free" or "cheap" daycare. I think that if you really want your child to experience spiritual growth then that growth has to be a big part of the life of your family as a whole. It has to be something your kids see you modeling and passing on to them.