Alpha is a form of evangelism set up by the Anglican Church. It is funded from theological book sales and donations. It works different to conventional evangelism in so far as you go to them.
Would you object to a billboard advertising a humanism meeting?
I have very serious issues with the presentation of Alpha, and some of the people who run it. But sitting in on such a course or meeting is quite interesting. It doesnt hold any punches. You can ask what you like - infact it turns the percieved idea of what people think christianity is on its head. It goes back to the book.
For example - how many of you think that prayer is asking God for stuff, like a note to santa?
"Dear God can I have a new car"
Your wrong. Prayer has never been that.