From BiblePortal Wikipedia

Spots [1]

Jeremiah 13:23 (b) This is a very interesting type, and it contains a very special truth which we should observe carefully. The Ethiopian is black all over and knows it. It is impossible for him to change it. He may not even want to change it. This represents the sinner who lives in sin and knows that he is all bad, mentally, morally and spiritually. He also knows that he cannot change his condition. The leopard is black in spots. He also knows it, but it is powerless to change his appearance. This represents the sinner who thinks there is a great deal of good in him, and thinks there are just certain bad spots here and there, which he has never been able to change or remove, and perhaps does not care to do so. The case is hopeless with both of these. Only the miracle-working power of GOD could remove the black from the Ethiopian, or remove the spots from the other.

2 Peter 2:13 (a) Our Lord constantly warns against a union between the unsaved and the saved. In this particular warning, He is reminding us and informing us that when the ungodly mingle and mix in the service of the Lord, or the worship of the Lord with GOD's own people, they smear and blot and disfigure the services in which this takes place. The unrighteous and the unsaved have no place whatever in the service or the worship of the church.