Y'shua said many will come in His name and claim He is the Christ, but will ensnare many and lead them astray. He didn't teach a 'system', but the truth of God and what we are to do with it if we believe and have the roots in us to let it grow. As with Moses and the false leaders while Israel was in the desert, he said for those with him to get on his side, and whoever wanted to follow the other leaders to get to another place - God took care of them respectively as an example for us to note: following those who don't follow that Prophet will be cut off again.(Acts 3:22,23)<quoted text>
Are the "challenged individuals" truly in danger if they are in a false system? Or will God judge them according to what knowledge they have and act on it? What if you're in a false system?
And of the opening teachings He reaffirmed "Man shall not live by bread alone, but by every word that proceeds from the mouth of God." The gospel is still fully capable to be seen in the OT if you take the time to look the passages up that He was teaching from and explaining.
As those in Acts did - they went back to see if what they were being taught was actually the truth. We can do the same thing - so what excuse might we have if we follow a false prophet, teacher, preacher, angel or even one who presents themselves as the messiah? Since it still matters who we follow, how are we to know but by the directions God gave us through Moses and were also taught by Master Y'shua?
If we care, we'd better double check which side we're really on - according to what God has declared and blessed.