Lets start with some definitions:
"Skepticism or Scepticism has many definitions, but generally
refers to any questioning attitude towards knowledge, facts, or
opinions/beliefs stated as facts, or doubt regarding claims that are
taken for granted elsewhere."
Objectivity is a central philosophical concept which has been
variously defined by sources. A proposition is generally considered to
be objectively true when its truth conditions are met and are
"mind-independent"—that is, not met by the judgment of a conscious
entity or subject.
Bias is an inclination to present or hold a partial perspective at the expense of (possibly equally valid) alternatives.
Also worth noting is the difference between objectivity and bias:
Biased means a personal preference is expressed.
Objective means both or numerous sides are expressed without a preference being expressed.
And for "Christian viewpoint", one could refer to one of two positions (one more moderate and one more devoted):
Theism, in the broadest sense, is the belief that at least one deity exists.
Christian apologetics is a field of Christian theology that aims to present a rational basis for the Christian faith, defend the faith against objections, and expose the perceived flaws of other world views.
So what is the main difference between a skeptic, and a Christian theist? A theist believes that God of the Bible and Jesus exist (therefore, it is a "fact" to them, nor a mere "possibility"), whereas a skeptic takes no assumption (is neither agnostic, saying that one can't know if God exists, nor atheist stating that there is no God, but is open to the possibility that God might or might not exist).
What is a difference between a Christian theist and a Christian apologetic? An apologetic defends the faith against objections, and exposes the perceived flaws of other views. An apologetic is therefore biased towards his or her system of belief.
Good or bad at answering questions
What makes an apologetic better for answering theological questions? Quite often they know a lot on the subject of the given religion they support, and can present numerous claims supporting their viewpoints. They are devoted to proving their point right, so they will not try to omit any evidence supporting their claim, no matter how insignificant. So in general, they can present all there is about a given subject from the point of view of what they are supporting.
What makes an apologetic worse for answering theological questions? As per definition, they defend their faith against objection, which can be accomplished by not presenting alternatives to their views, or by misrepresenting some facts in their favour (for example, Kitzmiller v. Dover and claiming ID is not a religious belief). Moreover, sometimes apologetics resort to using faulty logic to prove their point (for example, even if one can prove that evolution is wrong, that would not prove intelligent design, despite some people implying that).
What makes a theist better for answering theological questions? By definition they believe in something, so they have to know at least a bit about the subject. They can be devoted to giving answers about their faith and could enjoy talking about the subject. Depending on their world view they can be more open to alternatives than apologetics and admit that some believes are not based on facts.
What makes a theist worse for answering theological questions? Some might not consider alternatives to their beliefs, some might choose not to mention it, or would be uncomfortable talking about it (taboo)
What makes a skeptic better for answering theological questions? They hold nothing as fact until it is proven, so they can consider and present more alternatives to a given problem. This can provide an insight that could be omitted by a theist (for example, Polish Catholics idolize pope John Paul II, but would seldom acknowledge him being conservative on doctrine, sexuality and ordination of women). Generally, they are comfortable exploring both sides of an argument and reaching their conclusion from it.
What makes a skeptic worse for answering theological questions? Generally, being a skeptic says nothing about one's interest or knowledge, so the person in question might not have any knowledge on a given subject. Sometimes skepticism can be close to pyrrhonism ("nothing can be known"), or contemporary cynicism (lack of faith and hope in human race), therefore rendering the "answer" into an open-ended "debate" with oneself. Skeptics disparage in regards to values hold sacred by theists can be viewed by some as trolling, or attempts at personally attacking them.
Which view is biased?
By definition, apologetics are strongly biased. Theists can be biased, but have an easier time being objective. Skeptics by definition are not biased in favour of the thing they are skeptic about, but they can be biased against that thing.
Which views are useful?
All of them. If one is looking for answer to a theological question based on a specific doctrine ("What does the Bible say about..."), an apologetic and a theist can present an exhaustive answer on the subject, as they are interested in learning a lot about their faith and scripture. If one is looking for an answer to a question that bridge between religious and non-religious world view ("Is there scientific evidence for creationism?"), a theist and a skeptic can remain objective on the matter and present a balanced opinion. Each view should be applied where it is relevant.
Apologetics are strongly biased, theists can be biased in favour of religion, skeptics can be biased against something. All can give good answers, but most in their area of expertise.