Justification is a legal term. In court, one accused of a crime is either condemned or justified. Based upon the merit of Christ, sinners are justified freely before God. His sinless life and substitutionary death on the cross for sinners is the basis for our justification, being justified freely by His grace through the redemption that is in Christ Jesus (Romans 3:24).
Sinners are justified freely by faith in Christ. Therefore, having been justified by faith, we have peace with God through our Lord Jesus Christ (Romans 5:1). Faith is trust and confidence, relying upon Christ alone. By faith in Christ, sinners are justified freely with God, and not by the works of the law (Galatians 2:19-20).
Sinners are justified freely by grace in Christ (Galatians 2:21). Faith receives the grace of God in Christ. Faith is the evidence that the believer is justified before God. It is the assurance of faith. Therefore it is of faith that it might be according to grace, so that the promise might be sure to all the seed (Romans 4:16). Be justified freely by grace, through faith in Christ.
Sinners are justified freely in Christ unto righteousness. The only way a sinner can become righteous before God is by faith in Christ. Righteousness is the gift of God. But to him who does not work but believes on Him who justifies the ungodly, his faith is accounted for righteousness (Romans 4:5). Be justified by faith in Christ.