Jesus says in Matthew 23: 9— “Do not call anyone on earth your father; for One is your Father, He who is in heaven.” The statement does not and could not mean that we can’t call our earthly fathers, “father;” for if it did, it would be contrary to the fifth commandment. It is an honor to call our earthly parents mother and father.
The statement was made by Jesus to a crowd, to His disciples, and by extension to all Christians throughout time. Jesus doesn’t want us to emulate the Jewish religious leaders He criticized for their selfish religious deeds and for their fondness of self-important status and titles (Mathew 23: 5-8). They took on these titles as a way of portraying themselves as father figures of the source of truth. We’re not to elevate ourselves nor have others elevate us to a status we don’t deserve.
Only God is the source of truth. Furthermore, only He is the source of life. As such, He is the only one able to give new birth. That’s how we’ve become new creatures. It was done directly by His will. In that sense, He indeed is our only Father. This, I’m sure, is what Jesus had in mind when He made the statement. He was speaking in the spiritual sense. When it comes to spiritual matters, God is our ultimate teacher. He is the only parent that we as new beings have, and He is the source from which all are to be raised in truth.
It is inaccurate, unbiblical, and belittling to our heavenly Father to think and speak of others here on earth as our spiritual fathers. This applies to Catholics who call their priests “father” and especially the pope as “holy father.” It applies as well to Protestants who are in the habit of referring to their mentors as “my spiritual father.”
Incidentally, I see and embrace this statement of Jesus as a principle not to apply any spiritual titles to humans that belong to God. That is why I also refuse to address anyone in the clergy as “Reverend.” Only God is to be held in reverence (Psalm 89: 7).