For me it was a little different, because I stopped believing that god sent people to hell when I was still in the church (charismatic evangelical -> Episcopalian pipeline). Once I accepted that god was most likely not externally-real (or if real, not worthy of worship), fear of hell had been gone for a while.
However, as a charismatic preacher's kid who observed and experienced a number of mystical experiences growing up in church, I can share what's helped me re-categorize them. While I was still a Christian, I would chalk it up to "god works in different ways for different people". But that still left me with "what about what I experienced".
For that, three things helped me a great deal.
Reading about the history of Spiritualism in 19th century America. The circles I grew up in were heavily influenced by "Word of Faith" preachers who were students of Kenneth Hagin. Having was himself a student of E W Kenyon. Kenyon repackaged 19th century Spiritualism with a "Holy Ghost" label stuck on it. The more I looked into it, the less likely it seemed that these preachers had a direct revelation of god and more likely that they were tapping in to whatever aspect of human existence those 19th century psychics were. That they would all decry Spiritualism as demonic, while claiming that what they preached was authentic (while remaining willfully blind to the common elemente) was an irony too rich not to take seriously.
Watching videos and reading accounts of Aikido sparring, then watching an Aikido master spar with a practitioner of another martial art. Being "slain in the spirit" is not solely a Christian phenomenon.
Remembering the first time that I, had each mystical experience (speaking in tongues, being slain in the spirit, experiencing a prophetic utterance). Isolating them from all the other times I experienced those things, and considering the original experiences on their own merits, I was struck that each time was accompanied by an intense feeling of being "outside the group" and an equally intense desire to be accepted by the group. With speaking in tongues, it was hearing my parents do it, and then telling them I could "pray in baby talk" too. With being slain in the spirit, I saw the expressions of peace on the faces of everyone else, and thought "the devil must have such a strong hold on my life that I can't experience god's power the way these other people can" and then decided to just fall over and see if I felt better. Conditioning myself to read the cues got easier and easier.
After a couple years in therapy, it became clear that much of what I witnessed as "Spiritual Warfare" could be explained by people attempting to repress (or experiencing catharsis of) negative emotions. Now, what I had always experienced as God and the Devil are nothing more than my experience of self-observed existence and my Shadow (to borrow a Jungian term). Will my categorization of those things continue to change? Probably. But the great thing about not being tied to dogma is that I can feel ok with where I am now, instead of always worrying that I'm somehow missing the mark.