In anticipation of Paul"s judgment he called on his Christian readers to examine themselves to make sure every one of them was walking in the faith. Testing themselves would preclude him having to discipline them (cf. 1 Corinthians 11:31). Paul believed that Jesus Christ was working in each one of them unless they failed this test. In that case there was some doubt whether they were walking in the faith. Paul himself claimed to be walking in the faith. [source][source][source]
This verse may at first seem to be talking about gaining assurance of one"s salvation from his or her works. [1] However this was not what Paul advocated here or anywhere else in his writings. He was writing to genuine believers ( 2 Corinthians 1:1; 2 Corinthians 1:21-22; 2 Corinthians 3:2-3; 2 Corinthians 6:14; 2 Corinthians 8:9). He told them to examine their works to gain assurance that they were experiencing sanctification, that they were walking in obedience to the faith. [source][source][source]
"Paul"s question is usually construed with regard to positional justification: were they Christians or not? But it more likely concerned practical sanctification: did they demonstrate that they were in the faith (cf. 1 Corinthians 16:13) and that Christ was in them by their obeying His will. To stand the test was to do what was right. To fail was to be disobedient and therefore subject to God"s discipline." [2][source]
"After twelve chapters in which Paul takes their Christianity for granted, can he only now be asking them to make sure they are born again?" [3][source]
"Fail the test" translates the Greek word adokimos (disqualified) which everywhere else in the New Testament refers to Christians (cf. 1 Corinthians 9:27). [source][source][source]
"In 2 Corinthians 13:3 Paul indicates that some of the Corinthians were seeking proof (dokimen) that Christ was speaking in Paul. Then in 2 Corinthians 13:5 Paul turns the tables on them and challenges them to prove themselves (dokimazo). What some of the Corinthians questioned was not Paul"s salvation. It was his sanctification. They questioned whether he was a true spokesman and apostle of Christ. Likewise, when he turned the tables he questioned their sanctification, not their salvation." [4][source]
". . . even though Paul asked the Corinthians to examine their objective standing in Christ, his remarks are structured in such a way that he knew there was no possibility they were still unregenerate. He asked them to examine themselves, not because he doubted their salvation, but because he was absolutely sure of their salvation, and that assurance formed an undeniable foundation for his appeal in 2 Corinthians 13:5 b and6. Paul"s jolting challenge in 2 Corinthians 13:5 a is best understood when placed in the context of his self-defense in the entire letter.... [source][source][source]
"The logic of Paul"s argument is compelling: If the Corinthians wanted proof of whether Paul"s ministry was from Christ, they must look at themselves, not him, because Paul had ministered the gospel to them ( Acts 18:1-11; 1 Corinthians 2:1-5)." [5][source]
"Nowhere in the Bible is a Christian asked to examine either his faith or his life to find out if he is a Christian. He is told only to look outside of himself to Christ alone for his assurance that he is a Christian. The Christian Isaiah , however, often told to examine his faith and life to see if he is walking in fellowship and in conformity to God"s commands." [6][source]
"Instead of a threat, Paul"s challenge in 2 Corinthians 13:5 is a sobering reminder about the true mark of a Christian"s ministry. The barometer of Paul"s ministry was people-the believers in Corinth, as well as those in Ephesus, Philippi, and other cities where he ministered. Eternally redeemed people were the proof of his apostolic authenticity and of God"s presence in his life." [7][source]