16. Salute one another with an holy kiss--So 1Co 16:20; 1Th 5:26; 1Pe 5:14. The custom prevailed among the Jews, and doubtless came from the East, where it still obtains. Its adoption into the Christian churches, as the symbol of a higher fellowship than it had ever expressed before, was probably as immediate as it was natural. In this case the apostle's desire seems to be that on receipt of his epistle, with its salutations, they should in this manner expressly testify their Christian affection. It afterwards came to have a fixed place in the church service, immediately after the celebration of the Supper, and continued long in use. In such matters, however, the state of society and the peculiarities of different places require to be studied.
      The churches of Christ salute you--The true reading is, "All the churches"; the word "all" gradually falling out, as seeming probably to express more than the apostle would venture to affirm. But no more seems meant than to assure the Romans in what affectionate esteem they were held by the churches generally; all that knew he was writing to Rome having expressly asked their own salutations to be sent to them. (See Ro 16:19).

JFB.