In the same boat here: 20+ years of hard core Christianity (Scottish Presbyterianism). Heavy, very heavy indeed studies lasting years and years. Regulative principle of worship, this kind of direction.

Was raised kinda an atheist though and converted in my 30s. A willful, well thought out decision to convert.

All came crashing down on me the moment I stopped ignoring some very obvious questions, e.g. who died on the cross?

Even some casual thinking about this lands you, inescapably, on the only conclusion you have available if you stick to the orthodoxy, and that is: a human nature died on the cross. Not God (cannot die) and, unfortunately for Christianity, not a human either (briefly: if JC is one person / two natures, you have to conclude his (human) nature died on the cross since JC the person, being God, cannot die).

At any rate, this is where it started for me and quickly escalated further. The entire New Testament, I'm convinced now, is a fraud and whoever pulled it off didn't even try to hide it. It's incredible how we can bullshit ourselves into believing what we (for whatever reason) want to believe. And not just religion.

In the end, the NT had to go leaving me with the Hebrew scriptures.