Marriage changes everything! Not only do the bride and groom change their status, lives and future, but their respective families are profoundly affected as well.
Every wedding is both a time of great joy and a time of heightened anxiety, and the preparation for one is a great balancing act. Each of the families wants to feel equally represented and validated, particularly when the love of bride and groom transcends religious boundaries! Bringing both traditions together in a harmonious way requires much communication, clarification of expectations, and compromise. I call this the three Cs of successful interfaith marriage planning.
To make the above three Cs work for you, you have to take the discussion beyond the wedding day itself. In my rabbinical work, I always try to spend more time talking about the couple's married life than about the wedding ceremony. For most people, with the exception of Britney Spears, married life is going to last longer than the wedding ceremony! The wedding ceremony ought to reflect the future life of the couple and not be a capitulation to the pressure of their families.
How do you make a wedding ceremony more than just a standard formulation recited by one or more officiants? Since my experience mainly applies to Jewish-Christian ceremonies, I will limit my remarks to these types of events. This is not to say that my remarks couldn't function as a blueprint for other types of interfaith ceremonies.
The first step is to find a rabbi and a Christian clergy who are open to the idea of a shared ceremony. Look for clergy who see an interfaith ceremony as a symbol of unity. We all have our own ways of seeking closeness to God, but we do recognize that there is only one God. And with an interfaith wedding ceremony we symbolize that we have all come from our different backgrounds to stand before the one God and ask for God's blessing over the commitment which bride and groom are affirming. Find clergy who are willing to take time for you. The more you can talk with the people who will officiate at your wedding, the more personal and meaningful you will find their involvement.
The second step is to explore the elements each of the traditions can bring in and how to incorporate them in your own ceremony. The following elements in a wedding ceremony are distinctively Jewish: the ketubah (wedding contract), recitation (or chanting) of the sheva b'rachot (seven wedding blessings), usage of a chuppah (wedding canopy), and the breaking of the glass. Typical Christian elements in weddings are biblical readings, the lighting of a unity candle, the blessing of the rings. Elements shared by both traditions are the recitation of vows, the exchange of rings, a wedding homily, the blessing of the couple. Other cultural traditions reflecting the couple's ethnic backgrounds also make nice additions to the ceremony.
I strongly believe the rabbi and Christian clergy should try to share the service halfway or at least not give the impression that one is dominating it while the other is just an addendum. It is important that the language used by the clergy is neutral enough not to offend anyone. What is lost in "true reflection of a religious tradition" is gained by keeping the ceremony harmonious and pleasant. I always try to minimize, or at least translate, the Hebrew and make sure that the priest or minister abstains from mentioning Jesus, Mary, or the Trinity. Basically everything is possible when both clergy are willing to work together. The more a ceremony can bring together the two traditions seamlessly, the more unity is present.
I prefer to share the service with the co-officiant in a way that we alternate in leading the ceremony and its different parts and address both bride and groom. For example the priest or minister does the ring exchange, and I lead the couple in reciting the vows. My assistant, who officiates when I have prior engagements, has recently been asked to chant the sheva b'rachot while alternating with the co-officiating minister who is reading the translation. A double blessing indeed!
The couples I have married, as well as their families, have said that their qualms about the marriage were greatly dissipated by having both sides equally affirmed in the ceremony.