Preaching Christ not done to isolate him in the minds of their listeners

In Scriptures people are asked to teach their children diligently and to go out to tell everybody and to reason about the importance of faith in Christ, Jeshua or Jesus Christ being the sent one from and son of God bringing people to God and to salvation..

How do you keep an eye out for heretical teachings?

So many centuries after Jesus and his apostles died there are more people giving preference to present day teachers, theologians and philosophers, instead of giving ear to the biblical writers or scriveners than in Jesus' time.