It is the doctrine of the Brotherhood of the Cross and Star not to wear shoes into the Bethels or the house of worship, in recognition and reverence of the holiness and presence of God.
Exodus 3:5 [KJV]  And he said, Draw not nigh hither: put off thy shoes from off thy feet, for the place whereon thou standest is holy ground.
Acts 7: 33 [KJV]  Then said the Lord to him, Put off thy shoes from thy feet: for the place where thou standest is holy ground.
Romans 10: 15 [KJV]  And how shall they preach, except they be sent? as it is written, How beautiful are the feet of them that preach the gospel of peace, and bring glad tidings of good things!
John 4:23-24 [KJV]  But the hour cometh, and now is, when the true worshippers shall worship the Father in spirit and in truth: for the Father seeketh such to worship him.  God is a Spirit: and they that worship him must worship him in spirit and in truth.