“being justified as a gift by His grace through the redemption which is in Christ. Jesus” (Rom 3:24 NAS95S)...note that the "justification" is the gift here as a result of the cross.
“For if by the transgression of the one, death reigned through the one, much more those who receive the abundance of grace and of the gift of righteousness will reign in life through the One, Jesus Christ.” (Rom 5:17 NAS95S)...note that "righteousness" is the gift that we "receive".
One other thought…God has also defined faith in the scriptures as choosing to believe. “But to the one who does not work, but believes in Him who justifies the ungodly, his faith is credited as righteousness” (Rom 4:5 NAS95S). "Believes in Him" is defined as "his faith" and further defined as "the one who does not work". Believing is not a work, it is called faith.
So, my faith or God's gift?…how 'bout BOTH