You're mainly talking about the modern USA, not the modern West. And USA happens to be the most Christian of Western nations. In other Western countries, too, the state religion is roughly proportional to Christianity. UK, for example, is midway between USA and Sweden in both respects.
Unless state religion causes Christianity (unlikely, IMO), that leaves us with two possibilities: either Christianity causes state religion, or they are both just different faces of the same mentality. In either case, your assertion that "Christianity is now mostly harmless" is wrong.
Unless state religion causes Christianity (unlikely, IMO), that leaves us with two possibilities: either Christianity causes state religion, or they are both just different faces of the same mentality. In either case, your assertion that "Christianity is now mostly harmless" is wrong.