‘Who will also confirm you to the end, unreproveable in the day of our Lord Jesus Christ. God is faithful through whom you were called into the fellowship of his Son, Jesus Christ our Lord.'
Note here the promise that they will experience this because they will be ‘confirmed' to the end (bebaioo). This verb is used as a legal term to indicate guaranteeing security. It is used in Hebrews 13:9 of those whose hearts are strengthened (confirmed) by grace. And Who is the One who will confirm us to the end? It matters little whether we see this as referring back to Christ Jesus (1 Corinthians 1:7) or God (1 Corinthians 1:4). The latter is supported by the words in 1 Corinthians 1:9, for otherwise the faithfulness of God in the matter comes in somewhat abruptly. The former is supported by the closeness of the antecedent. But either way the confirmation is by the Godhead, and is linked with God's faithfulness in that we learn that He is faithful in carrying out this very purpose.
Just as the testimony of Jesus Christ was ‘confirmed' in them by the Holy Spirit as He ‘sealed them unto the day of redemption' (Ephesians 4:30), guaranteeing their security (1 Corinthians 1:6), so now we also learn that either God Himself or the Lord Jesus Christ Himself guarantees their security, ‘confirming' them to the end, and guaranteeing that they will be unreproveable in that day. Thus Paul can speak of, ‘Being confident of this very thing, that He who began a good work in you will perfect it until the day of Jesus Christ' (Philippians 1:6).
So the true people of God are seen as being safe and secure in His hands. They can rely on the faithfulness of God. But there is another side to the picture. The test that they are His people is that He will continue within them His sanctifying work, changing them from glory into glory as they behold His face (2 Corinthians 3:18) that they may be presented perfect before Him, holy, unblameable and unreproveable in His sight (Colossians 1:22). That they will be presented unreproveable is guaranteed because He is the One Who ‘confirms' them. They may stumble but they will not ultimately fall. God will work in them to will and to do of His good pleasure (Philippians 2:13).
‘In the day of our Lord Jesus Christ.' This is the day when His people come before Him to receive His blessings, to give an account of their stewardship (1 Corinthians 3:10-15; Romans 14:10-12), and to receive praise from God (1 Corinthians 4:5). It is the day of the Lord's final triumph.
The ‘day of Christ' differs from the day of the Lord in that the latter refers more generally to God coming in judgment and finalising His purposes for creation (1 Thessalonians 5:2; 2 Peter 3:10), while the day of Christ and its parallels speak of the day when He comes for His own (1 Corinthians 1:8; 1 Corinthians 5:5; 2 Corinthians 1:14; Philippians 1:6; Philippians 1:10; Philippians 2:16; 2 Thessalonians 2:2; 1 John 4:17). Both occur within the final activities of God at the end of time, but looked at from a differing viewpoint, the one pointing to the day when Christ deals with His own, the other with the time when God brings all things to summation.
‘God is faithful.' The One Who has called us into the fellowship of His Son Jesus Christ our Lord, is totally faithful. This is the final guarantee of what has gone before. The Spirit has sealed us, and Christ and God will ‘confirm' us, for all rests, not on our faithfulness, but on the faithfulness of God. And none is able to pluck us from His hand (John 10:29).
‘Called us.' This is effectual calling, and guarantees the future of those called (2 Timothy 1:9; 1 Peter 5:10). In the end the reason why men respond to Christ is because they have been given to Him by the Father (John 6:37; John 6:39) and because the Father draws them to Him (John 6:44).
‘Into the fellowship of His Son Jesus Christ our Lord.' The idea here is of fellowship with Him. The word for ‘fellowship' (koinonia) signifies communion, fellowship, close relationship, full sharing. It is a favourite expression for the marital relationship thought of as the most intimate between human beings. Thus the idea is of such a close relationship with Christ that nothing can part us. It is an indissoluble union. But it is also a unity that demands being conformed to the One with Whom the union is made. We cannot speak of ‘fellowship' without thinking in terms of conformity (Romans 8:29). ‘How shall two walk together, except they be agreed?' (Amos 3:3).
Others would read it as meaning the fellowship of His people established by Jesus Christ, but the context demands that a close relationship with Christ be in mind. It is because we are ‘in Christ' that we are secure (1 Corinthians 1:2; 1 Corinthians 1:5). Thus we are members of His body in the closest possible sense (1Co 6:15; 1 Corinthians 6:17; 1 Corinthians 10:16-17; 1 Corinthians 12:12-27; Ephesians 5:30) and fitly framed together in Him (Ephesians 2:20-21).
It may be asked. ‘If Christians are so secure in Christ, how do we explain those who fall away?' The answer is one of two, either that such people never genuinely committed themselves to Christ from the heart, never really trusted in the saving work of the cross, whatever the outward appearance, were never really in Him. It is that they were converted to an idea, or the friendship of the church, or because someone they loved was a Christian, or because they liked some part of the message which suited their particular viewpoint, or for some other similar reason, and not to true submission to the living Christ. Or alternatively that while being marked off as His, they are being allowed to stray for a while, but can be sure that the Shepherd will seek them until He finds them (Luke 15:4). He will not let them finally stay away. All stray at some point, for every deliberate sin is a straying, but some take longer to be returned than others. Yet, if they are His, returned they will be, for His reputation as a Saviour is at stake.
‘How then,' it may be asked, ‘can we have assurance that we are His?' And the answer is, by the genuineness of our response to Christ and the assurance of the Spirit within. This is revealed in our genuine awareness of sin, by our genuine recognition that only through His finished work on the cross can we find forgiveness and salvation, by our genuine response to Him on this basis, by our desire to please Him (not the church or people within the church or Paul or Apollos or Peter or any other outstanding personality, but Him) and our desire therefore to do always what is pleasing to Him. In the end it is final perseverance which is the proof of salvation, for Christ does not fail in His work, but our confidence should be, not in that final perseverance, but in the Saviour in Whose hands we are and Who will bring it about. We may fail, but if we are His He will pick us up again and set us on the right way.