How do you truly feel certain that Islam is the truth?

Assalamu alaikum! May Allah’s peace be with you all. I hope everyone is doing well. I wanted to share something that’s been on my mind for a while. I’m going through a tough time with my iman. So many questions keep swirling in my head, and I can’t seem to find answers. Let me give you some background. I was born into a Muslim family in a country where Islam is the majority, but the practices here are sometimes called deviant by Arab Muslims. Honestly, I see their point-some of what people do feels more cultural than Islamic. But here’s what bothers me: the people around me genuinely believe their actions are part of Islam. For example, the way Shia Muslims observe mourning might look completely irrational to Sunnis, yet for the Shia, it’s deep devotion. So I start thinking: what if I’m in the same boat? What if I’m convinced I’m right, but actually I’m mistaken-just like I see others being mistaken? This makes me wonder about other faiths too. Their rituals seem odd to us, but they approach it with sincerity. They’d probably find our worship strange as well. So how can we be sure that we’re on the straight path and not just trapped in an illusion? I hope that question makes sense. Sometimes these doubts get so intense that the only anchor keeping me in Islam is the sense of purpose it gives. Without Islam, my life feels meaningless-it’s what gives me direction. But I still can’t stop wrestling with these questions.