“A disciple is not above his teacher, nor a servant above his master. It is enough for a disciple that he be like his teacher, and a servant like his master. If they have called the master of the house Beelzebub, how much more will they call those of his household!”
Matthew 10:24-25

In context, these words of Jesus are a warning to those who follow Christ, that since people persecuted Him, they will also persecute His disciples. As a general principle, however, these words also present a generality regarding the relationship between teachers and their students—that is very generally true. They are not, however, ironclad, denying any exception to the rule. There are students who grow beyond their teachers. Don’t all good parents desire that for their children?

Nevertheless, the general rule of thumb does instruct us to be cautiously discerning when it comes to which teachers we study under. After all, a student does become like his teacher. For better or for worse. Therefore, we should listen to, read, and follow the best teachers available. I selected a seminary and doctoral program based on who the professor of systematic theology was. I didn’t want to be taught just any old thing!

This is true even in selecting a study Bible. Look at the content of the teacher’s ministry, and look at the character of the teacher’s life. Don’t settle for much less than the best available to you.

That said, since no teacher (except Christ) is without flaw, we do not want to be so discriminating that we cut ourselves off from all teachers for fear of contamination. Pray always for your teachers and for discernment for yourself.

A theological footnote: The life-long process of sanctification is about progressively growing into the image and likeness of Christ. This is happening in the redeemed even when said growth is taking place slowly! But be encouraged by Philippians 1:6:

Being confident of this very thing, that He who has begun a good work in you will complete it until the day of Jesus Christ…