Chapter 29: Lord's Day 29
Section 81. Q. 81: Who are to come to the Lord's table? A. Those who are displeased with themselves because of their sins, but who nevertheless trust that their sins are pardoned and that their continuing weakness is covered by the suffering and death of Christ, and who also desire more and more to strengthen their faith and to lead a better life. Hypocrites and those who are unrepentant, however, eat and drink judgment on themselves.
Section 82. Q. 82: Are those also to be admitted to the Lord's Supper who show by what they say and do that they are unbelieving and ungodly? A. No, that would dishonor God's covenant and bring down God's anger upon the entire congregation. Therefore, according to the instruction of Christ and his apostles, the Christian church is duty-bound to exclude such people, by the official use of the keys of the kingdom, until they reform their lives.