What did God do after 'But God' in the passage?
After 'But God,' God, rich in mercy and moved by His great love, loved us even when we were dead in sins and filthy with Him; He reached down and quickened us, making us alive together with Christ, a picture of His resurrection.
Les explains that 'But God' marks the flip side after describing our former state as children of wrath by nature, disobedient, and enemies of God. It was not by any person, but by God alone, who is rich in mercy and acted out of His great love. Even while we were dead in sins and filthy with Him, God reached down, quickened us, and made us alive together with Christ. Les connects this to Romans, where God commended His love toward us while we were yet ungodly and sinners, and says this quickening pictures His resurrection.