Then said the Lord to him, Put off thy shoes from thy feet: for the place where thou standest is holy ground. Acts 7:33
Eastern Christians and Muslims always remove their shoes when they enter a church or a house. To sit down uninvited when in the presence of a ruler or a high government official is a breach of etiquette. But to enter a church, synagogue or mosque with shoes on it considered sacrilegious. Therefore it is not permitted. This is because the people believe that in church they are standing in the presence of God.
Moses was born and reared in Egypt. He was educated in the knowledge of all Egyptian sciences and religion. When at the palace, he had sat in the presence of Pharaoh, attended national ceremonies, and worshiped at the Egyptian shrines and temples. Moses had seen men taking their shoes off and bowing before the emperor and before the images in the shrines…
Reverence to God is man’s highest expression of respect. God does not want man to bow and beg, but it is proper to revere God and to enter into his house and before his presence clean, both inwardly and outwardly. To remove the shoes is symbolical of the removal of the earthly things and readiness to accept things of the spirit.
(Lamsa, George. New Testament Commentary, A.J. Holman Co., Philadelphia: 1945, pgs 53-54)