Not all forms of Christianity have disproved each other and not all criticisms are valid.
Denominationalism is a plague on Christianity. What it should boil down to is not one church doctrine against another, but whether it is found in the word of God, the Old Testament included.
The Law and the Prophets point to the coming Messiah, they give us the criteria by which one can recognize Him.
I'm afraid we disagree there. Protestants who argue amongst themselves do nothing but quote bible verses back and forth. Who wins that fight? If a Campbellite and a Calvinist quote bible verses back and forth, how do you tell who is right and who is wrong? And of course the ancient liturgical churches who point this out have the identical problem, only with contradictory traditions and claims of authority.
The Law and the Prophets point to the coming Messiah, they give us the criteria by which one can recognize Him.
Metmom . . . you and I agree about a lot of stuff, but we also disagree about a lot of stuff. Your assertion above is a claim of chrstianity. It is a claim--that's all. It is not self-evidently true, nor does asserting the claim prove it.
If you were to read the "old testament" without chrstian presuppositions (not easy to do, I know), you would find a very different religion. And of all the mitzvot in the Torah, there isn't a single one saying to "accept the Messiah" (just like there isn't a negative commandment against "deicide," which doesn't exist). The notion that the Torah is very primitive and the Prophets and Writings higher (culminating in the "new testament") is also a chrstian assumption.
Much of your position here is based on a reaction against Roman Catholicism. The Protestant/Catholic argument simply doesn't apply to this issue.