Because if it is true that Christ has paid the price for their sins, then why not? They are merely approaching God from a different angle, but their sins have been forgiven and they're just as justified as one who believes in Jesus Christ alone as their Lord, King and Savior.
True. I see your logic. Albeit, the conservatives in those mainline denominations would say that you leave out the crucial steps of repentance and faith in Jesus.
I, however, have come to think as you do.....that God opens the heart to faith. Logically, no other way to account for it.
I am looking for another denomination that will fully accept my ordination, be in the historic Christian tradition, not be beset by even a hint of these problems, and believe in salvation by grace through faith. I'm open to everything from A to Z, from Evangelical Congregational to Free Methodist to Orthodox.