Given the general integration of Jews into all aspects of society in the United States, it is very frequently the case that non-Jewish guests will be present at a brit milah ceremony. This could be because one of the parents of the baby is not Jewish and his or her family is attending or because non-Jewish friends, neighbors, and colleagues have been invited to this significant celebration.
The non-Jewish attendees will be both anxious and curious. They will be anxious about seeing the circumcision performed but will also be very curious about the brit milah ritual and other aspects of Jewish observance. Thus having non-Jewish guests at a brit milah ceremony provides a wonderful teaching opportunity.
The idea of commitment to God via a Covenant is not strange to Christian guests at a brit milah ceremony. In their own religious tradition they make a similar commitment to God through Jesus. It is often of tremendous interest for such guests to see where in the Bible, i.e. Genesis 17, the special relationship between God and the Jewish people comes from. The readings of the brit milah service, with its quotations from the book of Genesis, are usually extremely well received by non-Jews in attendance.
Moreover, the naming ceremony, analogous to a christening of a new baby for Christians, is easily understood and appreciated by non-Jewish guests. Their religious background renders them fully congruent with the religious and spiritual significance of bestowing a name on a newborn.
If there are non-Jewish guests that the baby’s parents would especially like to honor, they can fill any role except that of being a sandek (see “Honors at a bris“). They can be asked to light candles, to carry the baby in from the mother to the sandek, or to offer their own prayers for the baby’s health and well-being.