Why does Russia ban un-orthodox Christian religions?

Answer 1

Because that is Putin game. Unlike the Soviet atheist nation, Putin uses the Russian Orthodoxy to 'subvert' Ukrainians, Georgians, and others through migration and settling. Like he did in Georgia (the country, not the state in the US), if anything alarms the settlers, Putin acts like he has to protect them. It's a strategy of Subversion; insinuation, imposing, a bloodless revolution. To over populate an area in order to change the native paradigm. https://en.wikipedia.org/wiki/Subversion