Q. 171. How are those who receive the sacrament of the Lord’s Supper to prepare themselves before they come to it?

A. Those who receive the sacrament of the Lord’s supper are to prepare themselves for it before they come by examining themselves in the following ways: of their being in Christ; of their sins and needs; of the truth and measure of their knowledge, faith, repentance, and love to God and the brethren; of their charity to all people, forgiving those who have done them wrong; of their desires for Christ and of new obedience; and by renewing the exercise of these graces by serious meditation and fervent prayer.

WESTMINSTER LARGER CATECHISM, QUESTION 171