Help me guide my brother back to Islam – French version below

Salam alaykum everyone, I'm reaching out because I need some advice and support, and I know the Ummah has a lot of wisdom to offer. My brother is going through a really tough time with his faith. He recently told me he doesn't believe in Islam anymore or even in Allah's existence. It was a big shock for me and my family, but I want to help him find his way back, and I'm hopeful it can happen. I'm looking for people who have solid Islamic knowledge (like theology, history, philosophy, psychology) but also a kind and understanding approach. People who get the doubts our generation faces and can respond with logic, patience, and respect, not just authority. If you have any resources, personal stories, or tips on how to handle these conversations, please share them below. I'll read everything and follow up on what makes sense. Jazakum Allahu khayran for your time and kindness. May Allah reward you all. PS: We mostly speak French, so French-speaking perspectives are extra welcome, but I'm open to anything. I posted a French version in the comments since this platform doesn't allow French posts.