Second Corinthians 13:5 reads, “Examine yourselves as to whether you are in the faith. Test yourselves. Do you not know yourselves, that Jesus Christ is in you? — unless indeed you are disqualified” (NKJV). In this verse, Paul said each needs to look to his mind and actions to determine if they are in “the faith.” The definite article “the” is in the Greek, which means this is not talking about just a personal belief but about the system of belief (faith) or doctrine. There are rules and regulations that can measure one’s life and beliefs. To be “in the faith” means to be in the system of rules and regulations. Otherwise, Paul would have stated they should have faith, but he said people need to be “in the faith.”
Then, Paul stated that Christians have Jesus Christ living in them unless they are reprobates. So, if they are not living “in the faith,” Christ is not in them. If they do not have Christ living in them, they are not “in the faith.” This goes against what many religious leaders today teach. They say Christ can be in you if you just say you have a belief in Him. Some say nothing you do or think after that acceptance will take Christ from you. Some say there is no law that you must obey. Paul said a person must examine himself. If there is nothing I can do to alter my eternal destiny, then why bother to examine anything?
This letter to the Corinthians was written to Christians. Paul did not tell unbelievers that they must examine themselves (although this is a true principle). Paul told Christians that they must find themselves in the faith or they do not have Christ in them. Some religious leaders try to say that if the person examined himself and found he was not in Christ, then, he was never really in Christ. Yet, the very first verse in the letter says Paul was writing to “saints.” If these saints were not really Christians, then Paul would have been mistaken and not really inspired by the Holy Spirit. However, the apostle correctly addressed the epistle to “saints” or Christians, and he was divinely inspired.
Study your Bible. Learn all you can, and make sure you find Christ in you and confirm that you are in the faith.