So a friend of mine is arguing that in Matthew 16:18, Our Lord does establish his church on Peter but never confirms that it will never fall or that it wouldn't move or Christ's Church wouldn't be at one see forever.
Here is the line from Sacred Scripure:
And I tell you, you are Peter, and on this rock I will build my church, and the gates of hell shall not prevail against it.
Basically, he is using this argument to say that at some point in recent history, it could be possible that the "See of Peter," Christ's Church "moved" to one of the orthodox sees, like the Russian Orthodox Church. He believes that the Russian Orthodox Church might be the "New Rome" or the continuation of Christ's Church. He sites that the lack of a unified/definitive.true Magisterium in the church today makes its ministry invalid along with the bastardized sacraments.
I was wondering if any of you have heard such an argument before or know how to properly respond to it? I had never in my life heard anyone site Mathew 16:18 as a verse to support the validity/justification of a non-ROman church so I'm a little confused.
When I asked him if he considers himself a sede he said that he doesn't but because he believes the Russian bishops along with their Patriarch to be "successors" of that church which Jesus founded on Peter.