Do Christian’s still sin after they get saved ?

I’ve recently been hearing about this new doctrine that Christins can’t sin. It’s based of 1 John 3:9 and hundreds of other verses. It seems legit tbh. I mean how is the holy God gonna live in us if we still sin. Also, Matthew 5:48 says to be as perfect as the father. I don’t know. Eternity’s a long time to be wrong about something so I’m considerably all my options. I believe God is powerfully enogh to empower me to never sin again. Also 1 John 1;8 is referring to being born in sin, all of us are born in sin but when we get saved ( according to this doctrine) we go and sin no more just like Jesis said. What if this is the narrow way few find. Thoughts ?