ANSWER: Greeting one another with a "holy kiss" is mentioned several times in the New Testament (Romans 16:16; I Corinthians 16:20; II Corinthians 13:12; I Thessalonians 5:26; I Peter 5:14).
In the days of the apostle Paul it was a common custom in many nations for people to kiss each other when greeting or departing. A "holy kiss" was meant to display their love, sincere affection, and friendship for each other, and was a sign of peace. A kiss on the cheek or even on the lips is still a form of greeting in some countries today. However, the instruction to "greet one another with a holy kiss" was neither a law, nor a command from God. Rather it was simply a customary sign of greeting, much like the modern handshake or hug.
The important thing is that our greetings spring from genuine love, and friendship, and that they be characterized by sincerity and true Christian fellowship.