1559 · John Calvin, Institutes of the Christian Religion 4.17.40
Wherefore they are justly held guilty of the body and blood of the Lord, which, with sacrilegious impiety, they so vilely pollute. By this unworthy eating, they bring judgment on themselves. For while they have no faith in Christ, yet, by receiving the sacrament, they profess to place their salvation only in him, and abjure all other confidence. Wherefore they themselves are their own accusers; they bear witness against themselves; they seal their own condemnation. Next being divided and separated by hatred and ill-will from their brethren, that is, from the members of Christ, they have no part in Christ, and yet they declare that the only safety is to communicate with Christ, and be united to him. For this reason Paul commands a man to examine himself before he eats of that bread, and drinks of that cup (1 Cor. 11:28). By this, as I understand, he means that each individual should descend into himself, and consider, first, whether, with inward confidence of heart, he leans on the salvation obtained by Christ, and with confession of the mouth, acknowledges it; and, secondly, whether with zeal for purity and holiness he aspires to imitate Christ; whether, after his example, he is prepared to give himself to his brethren, and to hold himself in common with those with whom he has Christ in common; whether, as he himself is regarded by Christ, he in his turn regards all his brethren as members of his body, or, like his members, desires to cherish, defend, and assist them, not that the duties of faith and charity can now be perfected in us, but because it behoves us to contend and seek, with all our heart, daily to increase our faith.