IT WAS NOT very long ago that Americans could cite tradition as justification for opposing interracial marriage or for limiting the number of Jews admitted to some universities or for barring women from practically any position of power and influence. But tradition’s grip, while powerful, is not immutable, particularly in a country whose pride, founding principles and prestige rest so heavily on the promise of equal treatment under the law.

As it pertains to equal rights for homosexuals, that promise has made lightning gains in the past year, as the nation’s fast-shifting attitudes toward same-sex marriage have been reflected in state legislatures, federal courts and the White House. Now the voters of Maryland, along with those of three other states, can help make a reality of the promise of genuine equality for gay men and lesbians.

By voting for Question 6 next week, Marylanders would ratify the state law allowing gay men and lesbians to wed. We hope they do.

More than 42 percent of Americans now live in states with some form of legal protection for gay couples, though just six states and the District of Columbia have legalized same-sex marriage outright. Only a narrow majority of Americans say they favor marriage rights for gay couples, but large majorities of young people say they are fine with it. The trend line is clear, and the arguments against gay marriage are losing force.

One of those arguments is that legalizing same-sex marriage somehow constrains churches and other religious organizations. But Maryland’s law has been written explicitly to protect clergy, churches and affiliated entities, who would not be required to play any role in ceremonies that run afoul of their beliefs.

Likewise, opponents of Maryland’s law have argued that traditional marriage is somehow under threat from same-sex unions. But they have failed to show that the proliferation of gay marriages — more than 100,000 same-sex couples are now legally married — has had any impact on overall marriage rates in America, which have been dwindling for 40 years. It is illogical to suggest that the denial of marriage benefits to homosexuals would in any way encourage or defend traditional heterosexual marriage.

Gay marriage has failed so far in every state, 32 so far, where it has appeared on the ballot. That string of defeats will be broken as public opinion shifts. The issue will be tested again next week by referendums in Maine, Minnesota and Washington state, in addition to Maryland’s vote. The tide of history is clear; the main question now is the tempo of change. Marylanders should take pride if they put themselves at the forefront of the move toward fairness.