How can I be sure Islam is true?

Assalamu alaikum. I grew up Muslim, but lately I've been struggling with doubts about religion. With each passing day I feel more distant. I see so much suffering and injustice - kind people put through terrible things - and it makes me question. I know life is described as a test, but I keep thinking: what if people follow religion mainly to cling to hope? I don't want to believe in Allah just because it's comforting; I want to believe because it's truly right. Sometimes I wonder if religion was encouraged to stop people from resisting oppressors. I watch loved ones endure unfairness and not fight back because of sabr, trusting they'll get reward. That sometimes feels like passivity. I also worry about how we treat dua. When something we ask for happens, we say Alhamdulillah and thank Allah. When it doesn't, we tell ourselves to be patient and hope for reward in the hereafter. At times it feels like we're just coping, and I start to suspect that belief is something people made up to hold onto hope. I really want Allah to be real, but it's hard to be sure when so many seem to follow religion without questioning. My iman goes up and down and I may sound like a non-believer, but I'm struggling. May Allah forgive me. If anyone can kindly share thoughtful answers or gentle guidance, I would truly appreciate it.