Thanks to YouTube, you can see his appearance on a talk show in 1989, under his Islamic name Yusuf Islam, where he appeared to approve of the fatwa of death against author Salman Rushdie.
A lot of people were shocked, because the singer-songwriter formerly known as Cat Stevens was known for his songs about peace and love.
But being pissed off at Yusuf Islam is the equivalent of shooting the messenger. After devoting his life to seriously studying Islam for more than a decade, it made sense to Yusuf that Rushdie should be killed for his improper depiction of the prophet. The lesson we should get from this is not that Yusuf is inherently evil, but that the Muslim religion can corrupt even someone like Cat Stevens who was previously a messenger for peace and love. And Yusuf later repented of his statements.
The problem is not Yusuf Islam, the problem is Islam itself. So I recommend that you enjoy his Cat Stevens music without feeling guilty about it. His best album ever is Teaser and the Firecat, but my favorite Cat Stevens song is Oh Very Young which seems to be a song about the impermanence of life and the hope that the next generation will create a better and more loving and peaceful world, before they get too old to care. There’s also a line about flying a great white bird into heaven, which I believe is based on Chinese mythology in which white cranes can fly to heavenly worlds.