I'm a member of a mainline denomination (the UMC), and attend a denominationally affiliated seminary (Boston University School of Theology). I attended an evangelical/Holiness Christian college, and I have friends from many sides of the Christian divide. Over time, I've begun to notice some significant differences between so-called "conservative" protestants (who might call themselves evangelical, orthodox, traditional, or a variety of other things), and self-proclaimed liberal and progressive protestants. As far as I can tell, the biggest differences concern what it means to be Christian and to live a Christian life, and who God is.
Currently, I'm taking a class on the doctrine of the Holy Spirit. Now, depending on your background, you'll have different images/ideas come to mind when you think of the Holy Spirit (we discussed this in class recently). Our readings suggested a variety of things about the Holy Spirit -- being connected to music, expression, release, love, justice... and from around the room people mentioned the image of a dove, or the wind, breath (so far, so good... though I'd never connected the Holy Spirit with justice -- then again, as I've learned, for liberal protestants EVERYTHING is about justice). Then it hit me -- we're not even thinking in the same categories.
For me, a Wesleyan charismatic/evangelical, the first though was of the Trinity (after all, GOD refers to the whole of the Trinity: Father, Son, and Holy Spirit -- I can't address God and then Jesus comfortably, as I've already addressed Jesus if I address "God," I can, however, address the Father and then invoke Jesus and the Holy Spirit... but that's another rant); after thinking of the Trinity, God whose inward nature is Love, I thought of tongues of fire (Acts 2 anyone?), holiness, power, and self-control. I can't help but connect those three images to Phoebe Palmer, Charles Finney, and John Wesley, but when I said that, my professor asked for help understanding why "self-control" made my list... It's in Galatians 5:22-23, right?
Paul wrote "...the friut of the Spirit is love, joy, peace, patience, kindness, generosity, faithfulness, gentleness, and slef control." I guess for me, especially after being surrounded by Holiness folk, 5:24 helps make sense of "the fruit of the Spirit..." as Paul wrote, "And those who belong to Christ Jesus have crucified the flesh with its passions and desires." After all, Paul wrote about the fruit of the Spirit in contrast to "the works of the flesh (5:19-21)," right?
Here's the crux of the issue, I think: conservatives think of holiness first in personal terms (hence, self-control being a mark of sanctification), and then spilling over into transformation of the world. Whatever our lobbying power, electoral clout, or well-intentioned abdication of Christian duty to the State, our real power comes from on high, and from the indwelling Holy Spirit working through us, to make us an effective part of the Body of Christ at work in the world. If we recognize that the Holy Spirit comes upon us like fire, cleansing and transforming us, then we might get out of the way and let the Spirit work through us, but before we can be effective instruments of the Spirit's power, we need to let the Holy Spirit transform us.
For conservatives, it's all about God's mercy, as demonstrated in the death and resurrection of Jesus, which allows us to be grafted in to God's Holy People; for liberals, it's all about God's justice, as demonstrated by the way Jesus and the Church care for the poor. While the former might too easily become individualistic and overly focused on eschatological rewards, the latter is deficient, even in terms of Jesus' quotation from Isaiah... After all, Jesus didn't read "The Spirit of the Lord is upon me, because he has anointed me to bring good news to the poor," and then stop. Jesus continued, "He has sent me to proclaim release to the captives and recovery of sight to the blind, to let the oppressed go free, and to proclaim the year of the Lord's favor (Lk 4:18-19)." Sounds like mercy to me (unless all captivity is somehow unjustifiable).
Until we rediscover conversion and personal holiness (and especially self-control), we should expect our churches to continue to decline, as we cannot offer hope to individuals as they struggle with personal demons of addiction, gambling, sexual promiscuity seeking gratification, and an American consumerist and therepeutic obsession with the self. Until we can invite people to put on Christ Jesus, be transformed from who they have been into who they should be (and only can be in Christ), then we should expect not only that our church rolls will decline, but that our social and political influence with non-members will continue to decline as well. Then, the UMC and other mainline denominations will become in the social and political realm what too many of our congregations already are in the spiritual lives of their communities -- impotent and powerless to combat the forces of Evil in the world.