The religious world speaks of Christ knocking at the door of men's hearts seeking entrance and promising that if they will open unto Him He will give them eternal life.  They base this false idea on a total misunderstanding of Revelation 3:20, which has nothing at all to do with the unsaved but is dealing with a church.  If God were appealing to unregenerate sinners for entrance into their heart, that would indicate that God did not know whether they were going to respond or not.  This cannot be true, for God knows all things. What would be the purpose of His appealing to someone that He knew was not going to respond?

The very foundation of God stands sure and it bears a seal.  And part of that seal is that "the Lord knoweth them that are his".  In His own time He visits each one of them and quickens them into divine life. In this life-giving work there is no powerless appeal to them for entrance, but rather an exertion of almighty power, sending forth the Spirit of Christ into their hearts, crying, Abba, Father (See Gal. 4:6).  Any open minded reader will observe here that God does not send His Spirit into their hearts in order to make them His sons, but He does that work because they are sons.  They are His by divine election.  He foreknew them in the covenant of grace before the foundation of the world and predestined them (Rom. 8:29-30).  You see, He knows those who are His sons and those who are not, and He does not send His Spirit into the hearts of those who are not His.  Clearly there are some who are "none of his" (Rom. 8:9) and whom He "never knew" in a covenant sense (Matt. 7:23).  There are some who are "of their father the devil" (John 8:44).  Such characters clearly are not members of God's elect family whom He chose in Christ Jesus before the world began (See Eph. 1:4).

David said, "In thy book all my members were written, which in continuance were fashioned, when as yet there was none of them" (Psalm 139:16).  And John said, "Jesus knew from the beginning who they were that believed not, and who should betray Him."  He knows those that are His, and these he exhorts to "depart from iniquity."  Notice the latter part of that "seal" in II Tim. 2:19. ---Elder Ralph Harris