Strangely, though, I agree with the watcher, when he says the following:

Many Christians today, especially liberal ones, are under the impression that they, not God's revelation in the Bible, determine doctrine. Some think that doctrine must be open to change or reinterpretation based on the changing times, popular opinion, for the sake of unity, or based on their feelings, emotions, and finite thoughts. When one reads blogs written by Christians, they might encounter statements such as these.

Now, leaving aside the "drive by" (in the watcher's own words) attempt to smear a fellow Christian as a liberal, I do agree that many people are entirely too...free with the idea of what could be called "theological license" and the notion that doctrine changes over time. But to be fair, I don't think doctrine is wholly static.

Let's take an example. Suppose, just for the sake of argument, that an alien ship lands somewhere in the world, and the pilots make themselves known to us. Okay...we have just seen it conclusively proven that alien life exists, that living beings exist on a planet other than our own.

How does this affect doctrine? Moreover, does this affect doctrine?

Without getting into C.S. Lewis' five points for consideration, the answer is that it does affect doctrine in one sense, but not in another. Obviously, any doctrine which specifically states that e.g. God made life only on the Earth would have to be disacarded as false. But a doctrine that states only that God is the creator of all things -- all life and all the Universe -- would still be entirely valid. Since God is creator, the aliens would be His creation as much as we are His creation also.

The doctrine that says that God is the creator, then, does not change, except in the sense that we would have to understand it as having a somewhat wider scope.

But that's only one example. Let's take another, this time from history.

It might seem odd for a Catholic to make use of Galileo, but there it is: Galileo's big discovery was the final nail in the coffin of a cosmological theory called geocentrism -- the assertion that the Earth is fixed, with the Sun and all the planets in orbit around it. Within a strictly literalist reading of Scripture, geocentrism is the logical theory for Christian doctrine to espouse; numerous passages speak of the Earth being fixed and immovable, and built on solid foundations. The Sun, in contrast, is said to move, halting at the whim of God in its passage through the Heavens.

But we know, from Galileo's discoveries (and those of others before him) that geocentrism is false; our solar system is heliocentric (e.g. the planets orbit the Sun), and the Universe is far more vast than just the expanse of eight planets and a few smaller hangers-on.

Christian doctrine in the early days of the Church was unabashedly geocentric in its view, and through much of the medieval age this remained the case. In the wake of numerous scientific discoveries, including Galileo's (and also Newton's later theories concerning gravity), the doctrinal teachings concerning geocentrism had to be changed to reflect what was understood now to be the reality of how the Earth and the Sun interacted with one another.

Now we see that doctrine sometimes must change, if God imparts revelation to us by some other means that challenges to think about how we interpret a passage of Scripture.

The watcher goes on to at least correctly define "doctrine", in terms of the actual word at least:

Doctrine is a truth, a principle or body of principles, a system of beliefs.

But after this, the watcher makes a bit of a mis-step

Christian doctrine is found in God's revelation to man, the Bible. It is not open for debate, it is not open to change, it is not open to compromise.

This is not wholly accurate. Doctrine is based on God's revelation, and specifically it is based a particular group's understanding of the Bible...but then in the sense that doctrine is drawn out of the teachings and messages contained within Scripture. It starts with the text of Scripture, but only emerges through exegesis and thought.

As an example, think of the way Calvinists teach a doctrine of predestination, while Methodists teach a doctrine of Prevenient Grace. Both doctrines are based on exegesis from the Bible, but the doctrines themselves contradict -- Wesleyian Prevenient Grace rejects Calvinist predestination, and vice versa.

And I think it goes without saying that Calvinists and Wesleyians have been debating this issue for centuries.

The watcher continues, getting another thing exactly correct:

As Christians, we are called to study God's Word and conform our lives in obedience to it.

But then the watcher continues:

Correct doctrine must form the foundation of our faith and take precedent over unity, our feelings and emotions, relationships, etc. We encounter incorrect doctrine, we are commanded by God' Word to rebuke and correct it, not compromise or accept it.

Here the watcher has contradicted himself somewhat, if we take into consideration his previous assertion that doctrine is unchanging. Why should we work to correct that which cannot be changed, unless doctrine is not unchangeable? Moreover, for what take we might demand in our working to change false doctrine, we must be willing to give in terms of changing incorrect doctrine.

The watcher adds this:

The entire Bible is doctrine. It is forever settled. It is unchanging. It is God's truth.

Is the whole of the Bible "doctrine"? Is Song of Solomon doctrine?

The Bible itself is the source of doctrine, but the watcher has confused the means with the ends. Doctrine emerges from Scripture through exegesis and, in its more intelligent expressions, due consideration of natural revelation as well. Good doctrine should not contradict the message and meaning of Scripture (whereas false doctrine will do so). And I will be the first to agree that God must be the first participant in any promulgation of doctrine.

If I didn't believe that, I wouldn't be Catholic, would I? ;)

Let's come back to Song of Solomon. It's a short book, but it serves as a good example here. What is Song of Solomon? At its most basic, it's a few pages of very erotic love poetry. Okay, so perhaps we can infer that it has something to tell us about sex (and indeed, it does). But not directly. Doctrines pertaining to sexuality and marriage will draw upon Song of Solomon as one source (another would be, of course, Jesus' teachings on marriage, and yet another source would be 1 Corinthians 7)...but the point is that the doctrine takes the Scripture as a source and, through some exegesis and comparison against other teachings in the Bible, forms out of Scripture.