There is a great difference between baptized and unbaptized people. According to the teaching of St. Paul in Galatians 3:27, “For as many of you as were baptized in to Christ have put on Christ,” and are made truly regenerate. They now have a freed will. As Christ says, they have been made free again (John 8:36). Therefore, they are able not only to hear the Word, but also to agree with it and accept it, although in great weakness (McCain, Baker and Veith).
But, as I have already said, we are not to pry into God's secret will, for the secret things of God are quite beyond us (1 Timothy 6:16). We should spend our time considering God incarnate, the Lord Jesus Christ, in whom God has made clear to us what we should and should not know (Colossians 2:3). It is true that the incarnate God says: 'I have longed to gather...but you were not willing'. Christ came to do, suffer and offer to all men all that is necessary for salvation. Some men, being hardened by God's secret will, rejected him (John 1:5, 11). The same God incarnate weeps and laments over the destruction of the ungodly, even though in his divine will he purposely leaves them to perish. It is not for us to ask why, but to stand in awe of God (Luther and Pond, Born Slaves).
Out of his immense goodness and mercy, God provides for the public preaching of his divine eternal law and his wonderful plan for our redemption, that of the holy, only saving Gospel of His eternal Son, our only savior and redeemer, Jesus Christ. By this preaching he gathers an eternal church for himself from the human race and works in people’s hearts true repentance, knowledge of sins, and true faith in God’s Son, Jesus Christ. By this means, and in no other way (i.e., through his holy word, when people hear it preached or read it, and through the holy Sacraments when they are used according to his word), God desires to call people to eternal salvation. He desires to draw them to himself and convert, regenerate, and sanctify them (McCain, Baker and Veith).