The love of God to His saints is not only from eternity in its being, but in its foundation; i.e. the love of God to His saints has not its foundation in anything temporal.

There are some that will allow that the love of God to the saints in its being is from eternity, but not in its foundation; but hold that it has its foundation in God’s foresight of that which is temporal, as particularly in the foresight of their holiness and good works. They suppose that the saints’ faith, and repentance, and obedience is the foundation of God’s love to them, and that God loves the saints from eternity no otherwise than as he foresees that they will in time believe, and repent, and live holy lives. So that though they allow the love itself in its being to be eternal, yet assert that ’tis the foresight of something temporal that is the foundation of it. But the love of God to His saints has not its foundation in anything temporal.

The ground of the love is eternal as the love itself.

He doesn’t love them from eternity, because he foresees that they will believe, and repent, and the like. The ground of His eternal love is not to be sought for in the saints, but in God’s own heart; that God loves the saints is from Himself, and not from them. His love is a free and sovereign love, and is from His own sovereign good pleasure, as we are taught. “According as he hath chosen us in Him before the foundation of the world, that we should be holy and without blame before Him in love: having predestinated us unto the adoption of children [by Jesus Christ] to Himself, according to the good pleasure of His will” (Ephesians 1:4–5). The love of God towards His people is self-moved. “The Lord did not set His love  upon you, nor choose you, because you were more in number than any people; for ye were the fewest of all people: but because the Lord loved you” (Deuteronomy 7:7–8).

The faith and holiness of the saints is so far from being the foundation of the eternal love of God that ’tis the fruit of it.

God has loved them from all eternity, and that is the reason that he has given them faith and holiness, and has brought them home to Himself truly to believe in, and love, and fear, and serve God; as in the verse of the text, “I have loved thee with an everlasting love: therefore with lovingkindness have I drawn thee.”

—Jonathan Edwards
“The Everlasting Love of God,” Sermons and Discourses, 1734-1738, 478–479.