I like to learn piano/synthesizer (keyboard) for church purposes - how long will it take?

First of all, I have learned just a little bit of keyboard and violin as a kid, but never liked it because it was more of my parents' interest than mine. But I always liked music and learned to play drums fairly easily. But I know Piano/synthesizer is a different animal. I am thinking about learning the piano so that I can play synthesizer in church. How long will it take to learn to a level where I can play in Church? I would say my comprehension and skill are probably about average.. I feel like I can pick out a song when I hear it and things..