My MacBook Pro says it's connected to the WiFi, but won't connect with Safari..? Any suggestions?

My MacBook Pro says it's connected to the WiFi here at our church, but won't connect to the Internet. Sometimes it won't even connect and it says "invalid password" or "connection timed out" even when we use the same password. I know its not our Router, because all of the other computers in the church work, and it connected this morning before the service, but it won't connect now. Does anyone have any suggestions?

For example, I just went to look at it and it works, but wouldn't work 5 minutes ago, and from past experiences won't work within the next 10 minutes. Has anyone else been through anything like this?

Message was edited by: MarbleHillUMC