If an imam in my area said “don’t boycott an individual cause of a sin, even if a Muslim breaks down a masjid he’s a sinner but still a Muslim who we shouldn’t boycott and avoid”. Should we not pray behind him because of him claiming that breaking down a masjid is a sin?

Ustadh AbdulAziz al-Haqqan

This statement is no reason to leave praying behind him, because a Muslim who commits a major sin is a sinner and does not leave Islam.