The church at Corinth had well-documented shortcomings. Nevertheless Paul referred to it as “those sanctified in Christ Jesus and called to be holy” (1 Corinthians 1:2). He explained that this was due to the fact that Christ was their “righteousness, sanctification (holiness) and redemption” (1 Corinthians 1:30).
1 Corinthians 1:2, 18-31