1 Samuel 7:3

If with all your heart you return to the Lord, etc. Here it is shown figuratively how the Lord teaching in Judea, performing miracles, suffering and rising, ascending into heaven and sending the grace of the Holy Spirit, made not only the Jews but also the Gentiles partakers of His mercy. Therefore, Samuel, having taken the priesthood after the death of Eli, addresses the whole house of Israel to remove foreign gods from among them.

And prepare your hearts for the Lord, etc. The Lord, author of a new priesthood, which is according to the order of Melchizedek, appearing in the flesh, teaches the whole house of Israel, that is, the Church of those desiring to see God, to remove from themselves the traditions of the Pharisees; and not only the works, which the law also taught, but also to prepare their hearts themselves to serve the Lord alone, saying: You have heard that it was said to the ancients: But I say to you (Matthew V.) Thus they can be freed from all enemies in the life to come.

6. But since, with God as our guide, we have followed the ark on its journey all the way to the place of its exaltation, let us see with what zeal the preacher keeps watch over the correction of those subject to him. For it continues: 'And Samuel said to the whole house of Israel: If you return to the Lord with your whole heart, remove the foreign gods from your midst.' Now what does Sacred Scripture customarily call foreign gods, if not demons, which dwell in handmade idols? We have said that in Samuel the new preachers of holy Church are signified. Rightly, therefore, he commanded the whole house of Israel to remove the foreign gods from their midst: because among the Gentiles coming to the faith, the order of preachers demanded not only the truth of right progress, but also the condemnation of ancient superstition. For it would profit them nothing to honor the truth by professing it, or by rendering obedience to it, unless they had first abandoned what is false as worthy of detestation. Whoever even now is placed within holy Church through faith, yet is rebellious against God through wicked conduct, must be admonished to remove the foreign gods from his midst. For even if he detests handmade idols, he is nevertheless subjected to the commands of demons through depraved action. But he casts the foreign gods away from his midst who is so converted to God that he never venerates unclean spirits through evil works. 7. A zeal for a more cautious life can also be indicated through these words of exhortation. For what is in our midst, if not our heart? Yet there are some who are defiled by the weakness of their heart and the habit of depraved thought, even while engaged in the works of the world. They indeed do good things unceasingly, yet they never cease to think wicked thoughts. Since as many demons rest in their hearts as there are impure desires, they are urgently admonished to remove the foreign gods from their midst: so that they may offer to almighty God not only the uprightness of their work, but also the glory of interior purity. Hence it is fittingly added: 'And prepare your hearts for the Lord.' For he prepares his heart for the Lord who not only separates his mind from impure thought, but also illuminates it with the splendors of holy thoughts and virtues: so that, as if the idols had been cast away and crushed, he may make himself a temple of God;…