When I was Mormon I thought I had a very strong, intimate relationship with my Heavenly Father. I talked to Him all of the time and I thought he spoke to me through impressions in my mind and feelings in my heart. The problem was those impressions in my mind and feelings in my heart had led me to believe the Book of Abraham was exactly what Joseph claimed it was. Well, it is crystal clear that the BoA is not what Joseph claimed it was. So, those impressions in my mind and feelings in my heart are at a minimum not a reliable way to find out what is true. It could be that those impressions and feelings are created by me entirely. If they were sometimes true and sometime false, I could not tell the difference because they felt exactly the same. Yet, through these impressions and feelings I experienced God and felt his love, etc, or so I thought. That started my questioning that maybe there was no god, maybe I had never experienced him, maybe he was nothing more than an imaginary friend. I reviewed my entire life history looking for anything definitive that I could cling to that would say, "here, here is something that strongly suggests there is a god". But, I could find nothing, not in my own life or the stories of what has happened in other's lives. I have read of near-death experiences, "miracles", "fulfilled prophecies", "answered prayers", etc. Of course, I have learned to think like a scientist and a skeptic, so stories that might be convincing to others aren't to me.
Then, I also started looking into the history of the Bible which makes much of it look made-up, too. I learned the logical issues that make it impossible for a god (if one exists) to be both all-powerful and all-loving. I learned about the problems with Pascal's Wager. And why the evidence really looks like no thinking entity intervened during the evolution of species or the creation of galaxies and planets. I really came to think that there is no need for the concept of god; it doesn't contribute anything to our understanding of how anything came to be. I came to believe that it is most likely that god is just a made-up concept like fairies and ghosts. I acknowledge that one cannot prove there is no god (or no fairies for that matter). So, there might be a god of some sort existing somewhere, but I highly doubt it.