Albert Barnes Commentary 1 Corinthians 1:8

"who shall also confirm you unto the end, [that ye be] unreproveable in the day of our Lord Jesus Christ." — 1 Corinthians 1:8 (ASV)

Who shall also confirm you. This means He shall establish you in the hopes of the gospel. He shall make you firm bebaiōsei amidst all your trials and all the efforts that may be made to shake your faith and to remove you from that firm foundation on which you now rest.

Unto the end. This means to the coming of the Lord Jesus Christ. He would keep them in the path of holiness to the end of life, so that at the coming of the Lord Jesus they might be found blameless .

The meaning is that they should be kept and not be allowed to fall away and perish. This is one of the many passages expressing Paul's strong confidence that true Christians will be preserved to everlasting life .

That ye may be blameless. The word rendered blameless anenklētous does not mean perfect, but properly denotes those against whom there is no charge of crime—those who are unaccused and against whom there is no ground of accusation. Here it does not mean that they were personally perfect, but that God would so keep them, and enable them to evince a Christian character, as to give evidence that they were His friends and would completely escape condemnation on the last day. (See the comments on Romans 8:33-34).

There is no one who does not have faults; no Christian who is not conscious of imperfection. However, it is God's design to so keep His people, and so to justify and sanctify them through the Lord Jesus, that the church may be presented a glorious church, not having spot or wrinkle (Ephesians 5:27) on the day of judgment.

In the day, etc. This refers to the day when the Lord Jesus will come to judge the world. It will be called His day because He will be the great and conspicuous object on that day, and it is especially appointed to glorify Him. See 2 Thessalonians 1:10: When he shall come to be glorified in his saints, and to be admired in all them that believe.

The term “confirm” also means “establish.” For the phrase “confirm you,” compare 1 Thessalonians 3:13 and 1 Thessalonians 5:23–24.