What is the significance of "solo Christo"?

from the old testament

• The Old Testament does not answer the question of the significance of “solo Christo.”

from the new testament

• Solo Christo is the principle that we are saved on the basis of Christ's sacrifice on the cross alone. We are saved only by Jesus Christ, not by works or anything or anyone else (Ephesians 2:8–10; John 3:16–18; 14:6).
• The Bible teaches that Christ's work on the cross is the singular basis for our salvation. Christ is the one who took our sins upon Himself on the cross (Galatians 3:13; Revelation 5:9).
• Romans 5 illustrates even further that Christ alone is the means of our salvation: "For it, because of one man's trespass [Adam], death reigned through that one man, much more will those who receive the abundance of grace and the free gift of righteousness reign in life through the one man Jesus Christ. Therefore, as one trespass led to condemnation for all men, so one act of righteousness leads to justification and life for all men. For as by the one man's disobedience the many were made sinners, so by the one man's obedience the many will be made righteous" (Romans 5:17–19). Paul leaves no room for question in this passage—Christ Jesus died so we may have justification, life, and righteousness.
• As the writer of Hebrews says, Christ's work was once and for all, and His blood secured for us an eternal redemption (Hebrews 9:12). "Eternal" and "once and for all" mean that no person can add on to Christ's work after the fact, not Mary or the Pope nor anyone else. Solo Christo.
• The Bible clearly teaches that we have done and can do nothing to deserve salvation (Titus 3:5). The New Testament writers warned again and again against adding law or rules to obtain salvation. Paul uses circumcision as a specific example of attaining righteousness or salvation through our works: "Look: I, Paul, say to you that if you accept circumcision, Christ will be of no advantage to you. I testify again to every man who accepts circumcision that he is obligated to keep the whole law. You are severed from Christ, you who would be justified by the law; you have fallen away from grace" (Galatians 5:2–4). If we try to gain our salvation through works, even a little bit, we have to gain all of it that way.
• We cannot partially try to fulfill the law and partially rely on Christ for salvation: "I do not nullify the grace of God, for if righteousness were through the law, then Christ died for no purpose" (Galatians 2:21). The Jews are not benefitted by following the Law, and neither is the Gentile following Gentile-placed laws (Romans 3:9–10, 22–23). In other words, Christ is all or nothing.
• Christ alone is the mediator between God and man; we do not need an earthly high priest because God Himself came down to earth to meet with us: "Since then we have a great high priest who has passed through the heavens, Jesus, the Son of God, let us hold fast our confession. For we do not have a high priest who is unable to sympathize with our weaknesses, but one who in every respect has been tempted as we are, yet without sin. Let us then with confidence draw near to the throne of grace, that we may receive mercy and find grace to help in time of need" (Hebrews 4:14–16).
• We do not have to go through a pope, priest, or pastor in order to meet with God. Rather, He calls us to boldly draw near to His throne. While the Bible supports confessing our sins to our brothers and sisters in Christ (James 5:16), we are still free to confess our sins straight to God, and in fact welcomed to (1 John 1:9).

implications for today

We can take great comfort in the tenet of solo Christo. It is Christ alone who secured our salvation for us, and we do not have to earn it through our good works. It is Christ alone who hears our prayers and knows our hearts fully, and it is Christ alone who loves us unconditionally while knowing our hearts completely. "He is able to save to the uttermost those who draw near to God through him" (Hebrews 7:25). Have you placed your faith in Him?