@engineer,
I agree.
The fiscally conservative segment of the Republican party are not perforce "Social Conservative" (read Evangelicals).
Many, if not most, probably tend towards socially conservatism but without the zeal and absolutism of Evangelicals: They don't want to outlaw abortion in all instances, but they do want to see it limited. They do think that minors who want an abortion should not be allowed to have one without the knowledge, let alone the consent of their parents. They don't want to force Gays to live, fearfully, in a closet, and they don't have a fundamental problem with them getting married, but they do want to see the institution of marriage ( between a man and a woman) endure.
Given a party that eliminates positions that currently seem extreme ( whether accurate or not), I've no doubt there would be a flood of people leaving the Democrats or coming out of apathy to represent.
There are very many young people who are fiscally conservative but shrink from a perception of a Republican Party that that hates Gays.
This is not to say that the Evangelicals are actually theocratic monsters, or that they have not been a valuable constituency of the GOP, but for good or bad, they are on the losing side of history.
We can choose to insist that their positions must be held by Republicans, or we
can take victories when we can and stave off the degradation of our society and our country by Progressives.
I don't expect them to compromise their principles and so the GOP needs to shunt them aside.
They couldn't produce a Republican victory in 2012, and so they clearly don't have the influence they lay claim to.
Political victory can 't be expressed as 100% for either party, and so the GOP needs to focus on a generally more conservative path fro the country.
Young people are happy to be fiscally and theoretically conservative, but they can't bring themselves to be associated with what they perceive to be Medieval strictures.
So yes, an Evangelical third party will benefit Republicans.