Joining a mainline church is a huge leap for your family as you leave the heresy that is Evangelicalism behind. There is freedom that is scary and you have to find a life outside of the church for the first time. Its like you go to church every Sunday to recharge your batteries to go into the world and make a difference. The siren song of fundamentalism has everything figured out for you. People care about you for just showing up and they pile on guilt to keep you in line.
My wife and daughter have and are reading a biography about MLK Jr. He is a modern time person who God has chosen to make a difference but used mainline theology to inspire him. Tillich, the Niebuhr brothers and others on staff at Union theological seminary inspired this man to make a difference.
This seminary is made fun of in conservative circles and written off as heretical. So what is it? Do we live Christ's example? Or do we live on every line of Paul's writing. I think that is the void between churches in America. Do we buy the Catholic beliefs or does the mix of tent revivalism and Calvinism show us the truth.
Who is more like Christ? MLK or the current Gospel Coalition schmucks? I think the guy who opposed culture and risked his life is more inspiring than a theological system that piggybacked itself on Nazi ideologies. The new Calvinist movement has no grace and might as well be Islam.