How do I know it’s all real?

My partner and I left the faith a couple months back, I won’t explain too much of the personal details about what actually happened since that’s a crazy long story. But we had a conversation and agreed that we would do one final search, we joined the faith for emotional reasons and left it the same way, so we want to see if there’s a way to research/know if Christianity is actually real if that makes sense, like the proof behind it. But we have no clue where to start. It feels sad after so many years deeply in the faith to suddenly be in this position, but I need a restart, if I’m going to follow a faith properly I want a stronger foundation. Any tips?