I went during Young Christian's Weekend a couple of years ago, and it was horrible. The crowds were out of control, the line-cutting was rampant and the people were amazingly rude. We had my daughter (who was one-year-old at the time) in a stroller, and the kids would literally shove the stroller out of the way if you were in front of them. It was completely chaotic, and I will never go back during that week. I was glad to see that the park is showing to be closed that day on the web site. That is the only bad trip to the park I have ever had in 30 years of going.
(And just in the interest of full disclosure, I am a Christian, and it saddens me that the worst weekend of the year is the one where the Christians are out and about.)