The Assignment
I need to find a formal definition of the term "holy kiss."

From Third Way Cafe:

The history of the "holy kiss" originates in the New Testament, where in four different letters from Paul to different churches, the early Christians are instructed to "greet one another with a holy kiss" (Romans 16:16, 1 Corinthians 16:20, 2 Corinthians 13:12, 1 Thessalonians 5:26). Some churches (not all necessarily Mennonite) take these passages to heart, and greet one another with a kiss on the cheek, much as anyone else would greet another person with a hug or handshake. This tends to occur in the more conservative churches, and was more prevalent in the past. In the conservative Mennonite and Amish churches where this practice continues, it is strictly understood that the holy kiss is shared only between persons of the same sex.

Most modern Mennonites read these passages in a cultural context. While we still greet one another warmly and offer blessings to one another in various ways, we usually don’t actually kiss.

From the Bluffton Singles Group Website, Apostolic Christian Church of America:

In view of the retention of this Biblical practice, the question often arises just why the church still adheres to this standard, because very few church denominations in the United States still greet their brethren with a holy kiss. The answer is straight from the Bible. The holy kiss is still implemented because the Bible commands it. While times change, the substance of the Bible does not.

The Word of God gives this commandment, not just once, but five different times. And this is not merely a directive incorporated in the Old Testament law (and thus made void through grace), but it is a clear and concise one intended for use in the New Testament church....

The first Christian churches were given this commandment in the instances listed below:

1. Romans 16:16 "Greet one another with an holy kiss".

2. I Corinthians 16:20 "Greet ye one another with an holy kiss".

3. II Corinthians 12:12 "Greet one another with an holy kiss".

4. I Thessalonians 5:26 "Greet all the brethren with an holy kiss".

5. I Peter 5:14 "Greet one another with a kiss of charity"....

Other New Testament accounts of using a kiss stand out clearly. Acts 20:37 reads, "And they wept sore, and fell on Paul's neck and kissed him". In Luke 7:45, Christ addressed Simon upon entering this Pharisee's home saying, "Thou gavest me no kiss". Further, in the heartwarming parable of the prodigal son, when the wayward son returns home in Luke 15:20 it reads, "And he arose, and came to his father. But when he was yet a great way off, his father saw him, and had compassion, and ran, and fell on his neck and kissed him"....

In the Apostolic Christian Church the use of the holy kiss is, of course, confined to each particular sex. That is, men salute men, and women salute women. Salutation between the sexes is exercised by a handshake and verbal acknowledgement....

It would admittedly seem somewhat unusual, and a departure from conventional behaviour, if a mere kiss was exchanged much like the custom of years ago as practiced in Europe and oriental lands. Because in earlier times it was customary for most anyone to give a kiss of greeting. Yet, the holy kiss which is practiced in Apostolic Christian assemblies is not the kiss that has its origin in social custom, but is a holy kiss with its origin founded in the will of God, and is included among the commandments of the New Testament. Obviously, there is a vast difference between the holy kiss, and the kiss of custom or form....

In his description of the worship service of the churches in the second century, Justin Martyr stated, "Then let the men apart, and the women apart, salute each other with a kiss in the Lord"....

As the early church grew and spread across the continents a gradual breakdown of the use of the holy kiss occurred. It seems that generally the kiss was universally practiced in the churches up until the end of the fourth century. From that time on the practice slowly began to disappear....

It was not until the beginning of the Anabaptist movement, which was an outgrowth of the Reformation occurring early in the sixteenth century that the revival, observance, and maintenance of the holy kiss was made on a large scale. This was particularly true in countries such as Switzerland, Germany, and Holland where observance of the holy kiss in the common fellowship of believers became nearly universal.

In a fellowship such as the Anabaptists, with an emphasis on a literal following of the commandments of Christ and the Apostles, with a stress on the infallibility, unity and authority of the Bible, and with a conscious attempt to re-establish the church on apostolic foundations, it is not surprising to find the spirit of love which characterized the early church, nor to find loves' most warm and Biblical expression, the holy kiss.

In addition to the Anabaptists other groups during the Reformation (and a few before) practiced the holy kiss. The use of the kiss was renewed by some of the medieval sects such as the Albigenses and Waldenses....

John Calvin, a leader of the Reformation during the sixteenth century commented on the holy kiss and said, "It was a sign of mutual love, and I have no doubt that Paul meant to encourage them to cultivate good will among themselves, not only in their hearts and in the duties which they were bound to perform, but also with that sign, so long as it was holy". In his commentary on I Peter 5:14, Calvin asserted; "Now he bids this to be the kiss of love, so that the sincerity of the heart might correspond with the external act."...

One of the most common reasons given for the non-use of the holy kiss is that the brotherly kiss was only a social custom at the time of the Apostles, and largely for that reason it is assumed both Paul and Peter incorporated it into their writings. They say that salutation type kissing was an ingrained procedure of that current culture, having been influenced by earlier societies - Oriental, Jewish, and others. And that since our modern culture no longer practices salutation type kissing; the Biblical directives in this regard do not apply, at least not in a literal sense....

While this explanation is made in sincerity, it is simply wrong. The Holy Bible...explicitly commands the use of the holy kiss. To assert that a warm handshake may be substituted for the holy kiss is adding to the Word of God. Also, a firm handshake or other "symbols" would not stand out, because unbelievers do these things as well....