1 Corinthians 1:8

By God’s sustaining power Christians will stand free of guilt before Him on that day. The day of the Lord Jesus Christ is the Rapture (cf. Philippians 1:6; Colossians 3:4; 1 Thessalonians 3:13; 1 Thessalonians 5:23; et al.). It is not the day of the Lord, which is a term both Old and New Testament writers used to refer to the period beginning with the Tribulation and extending through the Millennium.

"The expression ’the day of our Lord Jesus Christ,’ identified with ’the coming of our Lord Jesus Christ’ (1 Corinthians 1:7), is the period of blessing for the Church beginning with the rapture. This coming day is referred to as ’the day of the Lord Jesus’ (1 Corinthians 5:5; 2 Corinthians 1:14), ’the day of Jesus Christ’ (Philippians 1:6), and ’the day of Christ’ (Philippians 1:10; Philippians 2:16). (’The day of Christ’ in 2 Thessalonians 2:2 should be rendered ’the day of the Lord.’) ’The day of Christ’ in all six references in the N.T. is described as relating to the reward and blessing of the Church at the rapture and in contrast with the expression ’the day of the Lord’ (cp. Isaiah 2:12, marg.; Joel 1:15, note; Revelation 19:19, note), which is related to judgment upon unbelieving Jews and Gentiles, and blessing on millennial saints (Zephaniah 3:8-20)." [Note: Ibid.]

The Greek word translated "blameless" (anegkletos) means not reprovable or without accusation (cf. Colossians 1:22; 1 Timothy 3:10; Titus 1:6-7). It does not imply that at the judgment seat of Christ there will be complete equality among believers (cf. 1 Corinthians 3:10-15; 2 Corinthians 5:10). Moreover it does not mean that once God regenerates a person that one never sins again (cf. 1 John 1:6-10). It means every Christian will stand before the Lord guiltless, unimpeachable, because God has imputed the guilt of our sins to the Savior and He has borne them (cf. Romans 5:1; Romans 8:1).