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. - 2 Cor. 13:5
It is not uncommon to see this verse used to encourage professing Christians to examine themselves to see if they are genuinely saved. Though it is legitimate to encourage people to examine the veracity of the gospel they have believed in, after they have believed in the gospel, self-examination can become a discouraging exercise in futility. When the gospel of Jesus Christ ceases to be the focus of faith, believers can become lost in subjectivity and lose the assurance of their salvation, which undermines spiritual growth and maturity.
The Corinthians are told to examine themselves to see whether they are "in the faith," and to know whether Jesus Christ is in them. Nothing is mentioned about examining their works or their faith; that is foreign to the context. If works were to be examined, the Corinthians would fail miserably (1 Cor 3:1-3; 5:9-6:20; 11:21-30). Neither are they told to examine their faith, but to see if they are "in the faith."
One interpretation tries to answer the problems caused by self-examination for salvation by viewing these as tests of the Corinthians' walk with the Lord and not tests of their regeneration. In this view "in the faith" and "Jesus Christ . . . in you" refers to the quality of the Corinthians' relationship with Christ. However, it seems best to take "in the faith" as an objective reference to being in the Christian body of beliefs (see for example, Titus 1:13). Likewise, Jesus Christ in them would be another objective indication of their genuine salvation (1 John 5:11-13). Though this might seem to agree with the first view about Paul questioning their saved state, the difference is significant. Paul is not asking them to examine themselves because he doubts their salvation, but because he is sure of it. That becomes the basis of his argument for his own authenticity, something which the Corinthians were scrutinizing.
The Apostle Paul does not question the Corinthians' eternal salvation. Quite the contrary, he affirms it many times in this epistle (1:21-22; 3:2-3; 6:14; 8:9; and here in the context, 13:11-14). For him to cast doubts on their salvation or encourage them to question their salvation is against the tenor of both his first and second epistles to them.
Self-examination, by definition, diverts one's attention away from the legitimate object of faith, the gospel of Jesus Christ (His person, His provision, His promise), to a subjective self-evaluation. The assurance that comes from faith alone in Christ alone becomes impossible because of the subjective nature of evaluating our walk, our works, or our faith. Fortunately, there is a better way to understand this passage.
As usual, the context reveals the clues for the clearest interpretation. Paul is writing to the believers in the Corinthian church. They have many problems, some of which seem to be the result of false apostles undermining Paul's ministry. To exalt themselves, the false apostles are claiming that Paul is a false apostle (10:2). One of Paul's purposes for writing is to defend and humbly reassert his apostleship (5:12-13; 10:1-11:33; 12:11-33). The Corinthian Christians are confused and want "proof" (from dokimén, passing a test,being approved) that Christ is speaking through Paul (13:3). Paul tells them his power is from Christ, as they will see when he visits (13:1-4, 6).
The false teachers seek to "disqualify" (from adokimos, not passing a test, unqualified, disapproved) Paul as one who does not pass the test of an authentic apostle. But when Paul arrives, the Corinthians will see that he is not disapproved by God. The Corinthians themselves are his credentials of authenticity (3:1-3). Christ is in him because Christ is in them! Because they are surely saved, the Corinthians should know that Paul is not disqualified (13:6).
Thus Paul proves his authenticity by pointing the Corinthians to their own salvation experience. In the original language, "yourselves" is emphatic in the sentence throwing them back to verse 3 where Paul says, "since you seek proof of Christ speaking in me . . ." They should not examine Paul for Christ's presence, but themselves! Of course Christ is speaking through Paul, because Paul preached Christ to them and they were saved (1 Cor. 15:1-2; 2 Cor. 1:19), so Paul must be authentic. His argument here is the same as in 10:7 - "If you are Christ's, then we are Christ's." Only if they fail the test, would he.
One key to interpreting this passage is to note Paul's use of rhetoric and irony. In 2 Corinthians Paul uses highly emotional rhetorical language for emphasis (note especially the irony in chapters 10-12). The way the question is asked in verse 5, "Do you not know yourselves that Jesus Christ is in you?" expects a positive answer - "Of course you know that Christ is in you!" The wording of the original language in the phrase after that, "unless indeed you are disqualified," uses irony to mean the opposite - obviously they know they are not disqualified from eternal salvation. Verse 6 then follows with more irony - The readers were questioning Paul, but after looking at their own salvation they should know he has passed the test of authenticity too.
For Paul to cast doubt on the Corinthians' salvation would be contrary to his affirmations and declarations of their saved status which are ubiquitous in his epistles to them. Paul is motivating his readers to grow in their Christian experience not by having them question and seek their salvation again, but by recognizing and submitting to his apostolic authority and the truth he teaches (13:7-10). After twelve chapters of assuming and affirming their salvation, why would he now question it and undermine his whole appeal?
This passage should never be used to make those who have believed the gospel doubt their salvation by self-examination. On the contrary, this passage should teach us that the best way to motivate Christians toward truth and maturity is not by making them doubt their salvation, but by affirming it. The fact that we are saved by God's grace, belong to Christ, and have Him within us, is the best basis to appeal for godly attitudes and conduct.