I would say, yes Baptists are liberal, as are all Protestants. as you say, they all minimize doctrine except their own selections from it. Also, there are “conservative” baptists and “liberal” baptists, they aren’t all identical. Usually the definition revolves around cultural things, such as dress codes, hair length, feminist issues, stuff like that.
I would also say that yes, Catholic and Orthodox Christianity represents conservative, full gospel Christianity.
Mormons, being that they seem to be a special breed of religion within the Christian community, seems to me are mor liberal than many protestants, as their doctrines are extremely thin, poorly defined, and apparently change from time to time as political and cultural forces come to bear upon them (IE polygamy and Africans in the priesthood for example)
I don’t want to get into the old argument about ‘liberal’ versus ‘conservative’ here. In one sense, Protestantism does introduce a sort of liberal principle into Christian theology–it maintains private interpretation and personal experience as having nearly equal authority alongside Scripture and Tradition. This individualist approach to faith is very different from the Catholic/Orthodox understanding of submission to authority. Mormonism takes this element of individualism almost to an extreme, with it’s focus upon ‘personal revelation’ as a key to knowing what is absolute truth and what is not. Of course, even Mormonism has it’s own internal emphasis upon authority, so one can overstate that case if one is careless.
In another sense however, most Baptists and other Evangelicals are quite conservative, whereas Mormonism is at it’s core very radical. Evangelicals do accept the traditional canon of Scripture as authoritative. Moreover–they allow that private interpretation MUST submit itself to the normative sense of the whole Church from historical times forward.
There is an understanding among historic Protestants that something like the
sensus fidelium obliges every Christian to relinquish their personal or private views and to accept as true only those things which all Christians everywhere and always have believed and taught. The argument that Luther, Calvin and the other Reformers had with the CC is that they believed the 16th-Century hierarchy had abandoned the
sensus fidelium in some crucial areas. Most of the Reformers initially thought of themselves as doing no more than what St. Francis or other reformers had done for the Church previously: calling the hierarchy of that Church back to the roots of the Christian theology. Of course, the reforms ended up going beyond what those Reformers of the 16th century intended, but that is another matter.
Joseph Smith’s goal in the 19th century was also in some ways initially very conservative. He was part of a movement of Christians who believed that getting back to the true Faith received by Christians everywhere and always would take a special act of God–a revelation. Smith believed received just such revelations–or he pretended to receive them, as you will. (Frankly I think it a bit of both–that Smith probably knew on one level that he was engaged in ‘holy lying’, yet on another level felt that his goals and ends were Godly and God-inspired, therefore sufficient justification for what he was doing).
The problem is that Smith’s method is not the method used normatively by Christians to arrive at truth. Christians ordinarily had used Scripture, Tradition, and Reason, with Scripture being understood as a closed canon that held final authority over other methods. Smith re-opened that canon, and in some sense actually made each LDS believe a part of that open canon. Every believing Mormon in some way or another comes to their beliefs by way of a personal revelation from God.
And, that personal revelation, although it must submit itself to Joseph Smith’s revelations and to the Church he established, trumps Tradition and even Reason. This is why faithful Mormons do not treat the Book of Mormon as if it were a work of pious inspired fiction: they insist that it is genuine, unvarnished history, even if no generally accepted evidence presents itself to establish that claim. The Doctrine and Covenants, despite their zigs and zags in theology, are ‘true’ because the individual Mormon has received personal knowledge they are true. The Pearl of Great Price is true despite being bereft of any generally-accepted textual evidence, because Mormons ‘know’ that Joseph Smith is a true Prophet of God and that these books were translated by him by the gift and power of God. Etcetera.
It is in that sense that Mormonism is not merely ‘liberal’ in a way that Protestantism is not; rather, Mormonism is fundamentally radical, fundamentally different at it’s very roots from even Protestant Christianity. Mormonism is different from Christianity in it’s very epistemology.