Why Is Islam Growing in Some Places?

As-salamu alaykum - it's something I keep wondering about: why does Islam seem to be growing in parts of Europe while Christianity appears to be declining? I have a few thoughts and I want to share them humbly, not to spread conspiracy theories like the Great Replacement, but to try to understand social shifts. First, looking at Catholic countries: it seems to me the Catholic Church sometimes struggles to adapt to modern or postmodern times. The language of theology and the liturgy can feel hard to access for ordinary people, and there’s a historically ascetic outlook influenced by older philosophies. A strong central hierarchy can also make some communities feel distant or hard to reach. Islam, in contrast, often operates differently. Because there’s no single papal-style authority, there can be more space for local interpretation and practice, and that can feel more approachable to individuals. This decentralization can let grassroots Muslim communities form and grow, especially in poorer neighborhoods where local support and accessible religious life matter. I see similar patterns with Protestant groups in my country, Brazil. Evangelical churches have grown a lot in poorer areas because their local, decentralized structure lets them both spread and offer social support directly where it’s needed. I don’t have a clear answer for places with a strong Protestant tradition like England - I’m still thinking about that. I may be wrong on some points, and I apologize if I’ve unintentionally offended anyone. Please correct me kindly if I made mistakes.