The saying is trustworthy, for:
If we have died with him, we will also live with him;2 Timothy 2.11-14
if we endure, we will also reign with him;
if we deny him, he also will deny us;
if we are faithless, he remains faithful— for he cannot deny himself.
These verses call us to endure, so that in the future we may reign with Christ. The alternative to enduring is denying and being faithless (ESV). If we do that, the text is clear that Christ will deny us. This tells us that Paul is talking about a denial that goes deeper than what Peter did, because Jesus did not deny Peter but restored him. That fact alone shows us that this denial is not what we observe in Peter’s case.
What this denial consists in is further explained by the word, “faithless”. Since we are justified by faith, I take this to mean that the denial spoken of here is a repudiation of the gospel that is antithetical to being justified by faith. Faith is the apprehending of Christ with one’s whole being, holding on to him for forgiveness, salvation and life. Denying Christ in the sense spoken of here is the opposite of that: It is repudiating Christ in the firm belief that he is not faithful to do what he promises to do for us in the gospel.
How does a person evidence that they are repudiating the gospel in such a damning way? There can be greater or lesser manifestations of this repudiation of the gospel. A greater manifestation of it would be to simply repudiate the historical person of Christ altogether and to say, “I do not believe in Christ. I do not follow Christ. I put no hope in Christ.” But there are many lesser manifestations, but equally serious repudiations of the gospel. There are many who claim to follow Christ, but the Christ that they follow is not the Christ revealed in the Bible. They deny essential aspects of what the biblical gospel proclaims. There are also those who may adhere to an correct understanding of the gospel, but who do not live in accordance with what they profess.
If a person denies Christ in the way referred to here in these verses (and only God knows when the outward denial is the true expression of that inner state of eternal denial of Christ), Paul says that such a denial will result in Christ denying that person. However, in doing so, Christ remains faithful. His promise of salvation and forgiveness and eternal life, which all flow from his person and work on the cross, still remain the only hope for sinners. Christ “cannot deny himself” in the sense that his promise of salvation flows from who he is and what he has accomplished and it can never be changed or repudiated.
Paul emphasizes this to show the firmness of our hope in Christ. We must endure and hold on to him in faith, knowing that he is faithful and will never renege on his promise of salvation.