Romans 16:16

Salute one another with a holy kiss “The Jews considered the kiss as an expression of friendship. Thus Joab, pretending great friendship to Amasa, took him by the beard to kiss him, when he slew him, 2 Samuel 20:9. Our Lord says to Simon, Luke 7:45, Thou gavest me no kiss; meaning, that he had not expressed such affection to him as the woman had done who kissed his feet. Judas also kissed our Lord, pretending friendship to him, at the time he betrayed him. This manner of expressing friendship to each other the disciples of Christ adopted, and practised in their religious assemblies. So Justin Martyr informs us, in his account of the religious assemblies of the Christians, Apolog. Prayers being ended, we salute one another with a kiss, and then the bread and cup is brought to the president, &c. This was called the holy kiss, to distinguish it from the lustful kiss; and the kiss of charity, 1 Peter 5:14, to distinguish it from the treacherous kiss of Joab and Judas; being given as an expression of that sincere, chaste, and spiritual love, which Christians owed to one another. On the occasions mentioned by Justin, the men and women did not kiss each other promiscuously: the men saluted the men only, and the women kissed none but their own sex; as may be known from their manner of sitting in the public assemblies, described Apost. Constit., lib. 2. c. 57. On the other side let the laics sit, with all silence and good order; and the women, let them sit also separately, keeping silence. Then, after a long description of the worship, the author adds, Then let the men salute one another, and the women one another, giving the kiss in the Lord. Through length of time, and difference of manner, this method of sitting in public assemblies hath been changed. But that it was the ancient method cannot be doubted, being derived from the synagogue.” Macknight.