Romans 3:24b

and are justified freely by his grace through the redemption that came by Christ Jesus.

(v24, NIV)

This justification that is from God is by his grace. Grace is not merited and this justification is not worked for. Paul also mentions the medium or the method for this justification by grace. This is through Jesus Christ and the redemption that was brought about by him. Can't leave Jesus out of this. Jesus is central to the gospel and the justification of us sinners. It doesn't work without Jesus and it is only by Jesus that anyone is saved.