Romans 3:24 - Matthew Poole's English Annotations on the Holy Bible

Being justified freely by his grace; i.e. Being in this case, they can by no means be acquitted and freed from the accusation and condemnation of the law, but in the way and manner that follows. He mentions the great moving cause of justification first, (which doth comprehend also the principal efficient), that it is without any cause or merit in us; and by the free favour of God to undeserving, ill-deserving creatures, Ephesians 1:6,7 Ephesians 2:8 Titus 3:7. Through the redemption that is in Christ Jesus: the meritorious cause is expressed by a metaphor taken from military proceedings, where captives taken in war, and under the power of another, are redeemed upon a valuable price laid down: see Matthew 20:28 Mark 10:45 1 Timothy 2:6 Hebrews 9:12.