Edit: Eternal Oblivion

@necrodancer I think it's definitely possible for you to be happy without having religious beliefs! the whole "purpose" thing is overrated, and im seeing a lot more people come to the conclusion that their purpose is to be kind and make themselves and others happy, with or without an omnipotent god. it can be kind of freeing to a lot of people, because it becomes a "the only thing that matters is what I do here and now. I am going to take a break and take care of myself, the suns gonna explode anyway" type of thing, you know? if the "why are we here thing" still bothers you, theres a lot of philosophy that can be separated from a strictly religious point of view. I'm still very agnostic (and I've got quite a bit of religious guilt lol) but I don't think finding your own purpose or not finding solace in an organized christian faith makes anybody an inherently bad person or dooms them to unhappiness! in the same way that religious people find their way through the world through the lens of their religion, you can do the same through whatever sort of lens you choose.

@necrodancer There is a lot of controversy about the connection between religion and happiness.

Some research shows very clearly that religious people are happier, on average. This tells you nothing about your individual happiness. It's just an average.

But the research was mostly carried out in countries like the US, where atheists are in a minority. It could be that being part of a cultural majority makes people happier, on average. In countries like Denmark, where religion is not so much the majority culture, research shows that religious people are no happier than anyone else, on average.

See, for example: Does religion make people happier? Are atheists actually happier?

Overall, the answer to your question seems to be yes, it is possible to be happy and also a persuasive atheist. (The word evangelical traditionally implies preaching the Christian gospel.)

Charlie