I don't know Greek at all.
1 Cor. 6:11 says this in the SBL Greek New Testament: 11 καὶ ταῦτά τινες ἦτε· ἀλλὰ ἀπελούσασθε, ἀλλὰ ἡγιάσθητε, ἀλλὰ ἐδικαιώθητε ἐν τῷ ὀνόματι τοῦ κυρίου Ἰησοῦ καὶ ἐν τῷ πνεύματι τοῦ θεοῦ ἡμῶν.
Holman translates it this way:
And some of you used to be like this. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God.
My question is whether ἀλλὰ ἀπελούσασθε, ἀλλὰ ἡγιάσθητε, ἀλλὰ ἐδικαιώθητε ("you were washed, you were sanctified, you were justified") is in the singular or plural.
Was Paul using the singular, that individual persons were washed, sanctified, and justified, or the plural, that the entire church at Corinth was washed, sanctified, and justified? The point being, was the church saved en masse?