Verse 8
Who shall - confirm you - As the testimony of Christ was confirmed among you, so, in conscientiously believing and obeying, God will confirm you through that testimony. See 1Cor 1:6.
In the day of our Lord Jesus - In the day that he comes to judge the world, according to some; but, in the day in which he comes to destroy the Jewish polity, according to others. While God destroys them who are disobedient, he can save you who believe.