Charles Goodman designed three mid-century modern churches in the area — one each in D.C., Maryland and Virginia. The Unitarian Universalist Church of Arlington was the last of the three area churches, completed in 1964. An addition (see image below) to the church was added in 1994. While Goodman employed more concrete in this design a la the Brutalist style, he still managed to work in large expanses of glass to allow plenty of light into the sanctuary. Goodman also designed the 1957 Bethesda United Church of Christ that I highlighted here and the 1960s Christ Church of Washignton on Massachusetts Avenue in D.C.
Read this interesting Dwell piece on why Unitarian Universalist congregations have been drawn to modern design for their churches. View a photo gallery that includes other MCM Unitarian Universalist churches, including the one in Arlington and the Cedar Lane Unitarian Church in Bethesda, which I wrote about here.