Question: Bar Mitzvahs are on Shabbat, so why can't our wedding be on Shabbat?
Answer: Let me wish you and your fiance mazal tov. I wish you every joy in your marriage.
Your questions seems quite reasonable: Why can a bar or bat mitzvah be celebrated on Shabbat, but a wedding cannot? The answer has to do with the nature of Shabbat and the nature these two life-cycle events.
Shabbat is a time of rest, not just in the sense of "a day off from work," but in the spiritual sense of a time removed from the world of changing and making things. Shabbat is a time for just "being" and celebrating life, not for "doing." This is why Jewish tradition places restrictions on activities that are not appropriate for Shabbat.
A bar or bat mitzvah is the celebration of a young person's coming of age. We do not make the bar or bat mitzvah into something new with this celebration -- nature makes those changes happen without our help. Thirteen-year-old Jewish boys and girls become b'nei mitzvah (plural of bar or bat mitzvah) whether or not the occasion is celebrated.
By having b'nei mitzvah read from the Torah in the synagogue -- usually on Shabbat, but possibly on any other day that Torah is read -- we announce and rejoice in their coming of age. We also impress upon the young person the significance of being a responsible member of the Jewish community with all of its obligations. The celebration of the bar or bat mitzvah is not a private function; it is part of a regular, public worship service. When it occurs on Shabbat, it is part of the congregation's Shabbat celebration.
In contrast, a marriage ceremony is a special, private occasion in which two people change their status. Marriage in Jewish tradition is called "kiddushin," or "sanctification." The wedding ceremony sets the couple apart as united in holy union with each other.
Kiddushin, traditionally, is understood as an "acquisition." The groom takes the bride as wife. In modern times, we think of marriage as being a mutual act in which each of the loving partners "takes" the other. Either way, it is a "doing," a change in status, that cannot take place on a day devoted to rest.
In addition, there is a principle in Jewish tradition against mixing one celebration with another. We do not want to diminish the joy of bride and groom by celebrating their marriage on a day devoted to celebrating Shabbat any more than we wish to diminish the joy of Shabbat by attending to the separate joy of a bride and groom.
I receive many requests to officiate at Jewish weddings and couples often ask about weddings on Saturdays. Shabbat ends on Saturday at sunset, so it is possible to be married on a Saturday night. However, with the sun setting late in the summer, when most weddings occur, most couples choose to celebrate their Jewish weddings on Sundays.
I understand that you want to have a Jewish wedding. By that, I assume that you and your fiance are choosing to create a Jewish home for your new family. You can begin your marriage by making a beautiful Jewish choice together -- celebrating your marriage on a day appropriate for Jewish weddings. It will be the first of many choices the two of you will make together in creating a home in which Jewish tradition is cherished.
Mazal tov, Rabbi Jeffrey W. Goldwasser