NEW ROCHELLE, N.Y.

LIKE Hanukkah and Christmas, Passover and Easter, which recently coincided, can make for awkward moments for families that observe multiple religious traditions. For interfaith couples, the wedding season can also be a time for uncomfortable conversations: Who will solemnize our ceremony? Will God be mentioned — and if so, whose? Oh, and how will we raise our kids?

Before the 1960s, about 20 percent of married couples were in interfaith unions; of couples married in this century’s first decade, 45 percent were. (My definition includes Catholic-Protestant unions, marriages of mainline Protestants to evangelical Christians, and unions of those who affiliated with a religion and those who didn’t.)

Secular Americans welcome the rise of interfaith unions as a sign of societal progress. The relatively high rates of intermarriage of American Muslims, for example, suggest that their assimilation might resemble that of American Jews of earlier generations.

Even so, interfaith marriages often come with a heavy price. They are more likely than same-faith unions to be unhappy and, in some circumstances, to end in divorce. They also tend to diminish the strength of religious communities, as the devout are pulled away from bonds of tradition and orthodoxy by their nonmember spouses.