I'm afraid you're right about Romney and the bad old days.
As for a Christian party, do some googling about Abraham Kuyper and the Anti-Revolutionary Party. (Short version: Kuyper was the founder of a major conservative secession denomination in the Netherlands in the late 1800s, founder of a Christian university, founder of both Christian and general-interest newspapers, and a key promoter of a pre-existing Christian political party; he eventually became prime minister of the Netherlands.)
My theological background is Dutch Reformed — think Northwest Iowa and West Michigan, and connect the dots. That community was key to launching the candidacies of both Huckabee and Santorum in Iowa, and was an important part of Santorum’s support in Michigan. The Dutch Reformed were actively and aggressively talking about a Christian role in politics in the days when far too many evangelicals were saying politics was dirty stuff unworthy of Christian attention.
So is a Christian political party a good idea? If we had a parliamentary democracy, or proportional representation, or even more states with multimember legislative districts, I'd agree with you.
As long as we have winner-take-all single-member districts in most of the United States, and as long as the total number of conservative Catholics and evangelical Protestants is less than 50 percent in many parts of the United States, we have no choice but to work with economic conservatives and military conservatives if we want to win elections. The result is the three distinct but overlapping constituencies of social, economic and military conservatives are stuck together as a bickering family arguing among ourselves — if we split, we lose to the liberals.
I know this will sound like some of Newt Gingrich's wilder moonbase dreams, but long-term I would not be at all opposed to having more states with multimember legislative districts because it would make it possible for more people to be elected with strong ideological commitments on both sides of the political spectrum. A few places in the United States already have multimember districts, they're common in Europe, and they're much like the Republican primary system in most states. Basically, in a multi-member district, the top two, three, or four candidates out of all those running get elected. While that could be implemented fairly easily at the state level, it''s not possible at the federal level without a constitutional amendment, of course. Talk like that is so far outside the American political mainstream that it's not really very helpful, and I'm focused on trying to win elections in the current political situation rather than trying to make radical changes in that system.