Last year I became aware of and eventually signed The Manhattan Declaration, a manifesto drafted by Roman Catholic Robert George and Evangelical Baptists Timothy George and Chuck Colson and initially signed by a number of luminaries across the Catholic, Orthodox, and Protestant traditions. The Declaration states that the signatories, American Christians of a variety of traditions, unite to stand personally and in their institutional responsibilities for the sanctity of life from conception, the sanctity of one-man/one-woman marriage, and freedom of religious expression in the public square.
Each of these three elements requires an argument for what makes it biblical and essential to social ethics from a Christian perspective. I don't expect every Christian simply to agree with these things without thinking them through. At this time I'm not going to make the case for them, especially since the case is stated so well in the declaration itself. But I ask you to read the declaration and give it some thought. Please consider signing it and telling the people you know about it.