There will be an open house this fall.

One of the most beguiling buildings on the Beltway will have an open house in 2020.

Even before the election that could see the first Mormon president in U.S. history, the Washington region is becoming something of a Mormon stronghold.

Never lose your cool. That seems to be the mantra under which directors Reed Cowan and Steven Greenstreet operated in the making of this documentary. The film contains enough inflammatory information — about the efforts of the Mormon Church to ban gay marriage in California — to send any supporter of marriage equality into a rage. To their credit, the filmmakers present their story in a calm, even manner, wisely allowing the passions of…