2 Corinthians 6:18 - Matthew Poole's English Annotations on the Holy Bible

The latter words, which are a promise of God's reception of them who for his sake withdraw from a sinful communion with idolaters and scandalous persons, are taken out of Jeremiah 31:1,9, and teach us this: That none can reasonably expect that God should fulfil his covenant with them, who make no conscience of fulfilling their part in it with him; nor claim the benefits of a Father, who perform not the duties of his children: but on the contrary, those who are conscientious in the discharge of their duties of filial obedience, may expect from him both the kindness and the protection of a Father; which is the more valuable because he is the Lord God Almighty, who wants no power to protect them, or so to influence them, as to make them in all things happy, as the children of so great a Father.