Muslims are a cultural group. Catholics are a cultural group. Christians are a cultural group. They have a lot of things that are common among their group.
And there is no textbook definition of what a religion teaches. There are some churches that support gay marriage, some are hellbent on killing gays. You can't really say for sure what a religion teaches because these teachings are actually dictated by generally religions leaders and they come to different forms in different regions.
The other day I was reading a post on r/cryptocurrency which called religion a scam. That people are being scammed by religious leaders by the use of illusion of God or an external power. Logically speaking, only one religious creed could be true or all of them are false. Even if one creed turns out to be true, all the others are then false and therefore scams.
But people mostly general public doesn't really care about whether their religion is a scam or not or what it is about. They generally follow the religion their parents taught to them. The majority restrict it to following customs.
The Bible is against Homosexuality according to Romans 1. When churches approve homosexuality, they go against the Bible and therefore going against Christianity. Do you like Jihadism? Do you want Europe to die? You need to see that Europe is being murdered right now each day, right now, each day, like never before.