The title of Dr. Paul de Vries' recent article — "The Best Christians are Doubting Christians" (Part 1
and Part 2
) — initially struck me like lemon juice in the eye. Judging by the comments the article generated, I wasn't alone in my first impression of the writing.
Having read the article a couple of times now, I understand what Dr. de Vries is trying to say and fully appreciate the message he's attempting to convey. While I don't want to come across as some pedantic, uptight guy who's ready to make mountains out of molehills, there are times when terms do indeed matter. The point I'd like to make is this:
Doubt is not something valued in the Bible.
Now, I don't want to put words in Dr. de Vries mouth, but what I think he was trying to say is that the best Christians are thinking
Christians vs. doubting Christians. On that point I couldn't agree more and would argue that such a thing is what we're commanded to be in Scripture.
Doubt in the Bible
Sometimes exploring the Hebrew/Greek behind our English translations of God's Word provides a rich window into a deeper meaning of the term than our own language can provide. However, not in this case:
— 1. to have doubts concerning something, doubt, waver 2. to be uncertain about taking a particular course of action, hesitate in doubt. 
The word 'doubt', when found in the Bible, means exactly what you'd expect.
While Dr. de Vries says in his article, "I know of no Biblical passage where we are even warned against doubt," I would instead argue that 'doubt' is never used favorably in its context within Scripture (especially Romans 14:23, which explicitly links doubt and sin together):
"Immediately Jesus stretched out His hand and took hold of him, and said to him, 'You of little faith, why did you doubt?'" (Matthew 14:31).
"And Jesus answered and said to them, 'Truly I say to you, if you have faith and do not doubt, you will not only do what was done to the fig tree, but even if you say to this mountain, "Be taken up and cast into the sea," it will happen'" (Matthew 21:21; Mark 11:23).
"When they saw Him, they worshiped Him; but some were doubtful" (Matthew 28:17).
"And He said to them, 'Why are you troubled, and why do doubts arise in your hearts?'" (Luke 24:38).
"But he who doubts is condemned if he eats, because his eating is not from faith; and whatever is not from faith is sin" (Romans 14:23).
"But he must ask in faith without any doubting, for the one who doubts is like the surf of the sea, driven and tossed by the wind" (James 1:6).
"And have mercy on some, who are doubting" (Jude 22).
Dr. de Vries may try to label such verses as exhibitions of "unbelief" vs. doubt, but there's no getting around the term used, with the above verses in their context conveying a sense of uncertainty, a wavering, and the like in a negative sense.
In other words, doubt isn't a good thing.
Thinking vs. Doubting
Now as I mentioned upfront, I believe that the idea Dr. de Vries is aiming at is that thinking about spiritual matters is a very important thing, and in that regard, he is spot on. But there is a difference in careful and mindful scrutiny of truth claims and doubt.
In his book, Hard Questions, Real Answers
, Dr. William Lane Craig makes this distinction between doubt and thoughtful examination of belief:
When I was an undergraduate at Wheaton College, an attitude was prevalent among the students that doubt was actually a virtue and that a Christian who did not doubt his faith was somehow intellectually deficient or naïve. But such an attitude is unbiblical and confused. It is unbiblical to think of doubt as a virtue; to the contrary, doubt is always portrayed in the Scriptures as something detrimental to spiritual life. Doubt never builds up; it always destroys. How could the students I knew at Wheaton College have got things so totally reversed? It is probably because they had confused thinking about their faith with doubting their faith. We need to keep the distinction clear." 
As an example, it's one thing to think long and hard about why God allows evil to exist, but another thing entirely to doubt His goodness. While wrestling intellectually with theological matters such as theodicy sharpens our logical acumen and builds us up as we uncover answers, doubting God's omnibenevolence rots our faith.
Moreover, as Christians we need to steer clear of the postmodern concept of truth, which says no one can really no anything for certain (except, of course, that you can't know anything for certain…) Dr. de Vries quotes Paul who says we now see in a glass dimly (1 Cor. 13:12) and thus reaches the conclusion, "Consequently, we must doubt." But even he admits this doesn't mean we doubt all things. I'll add nor should we doubt things when it comes to God's truth.
I'm sure you'd agree the spirit that sows doubts with questions like "Has God said…?" is not something we ought to embrace.
On the contrary, Paul tells the Thessalonians that he brought the gospel to them with "full conviction" (1 Thess. 1:5), which literally means a "state of complete certainty."  In other words, there was no doubt in Paul's spirit as he delivered the gospel message.
When it comes to matters of the mind, although atheists and hardened agnostics make the exclusive claim that they alone are the ones who think logically and rationally, they couldn't be more wrong. The best Christians I know are powerful in the areas of logic and epistemology.
Further, skeptics overlook two important facts when it comes to faith and thinking. First, "faith" is never defined in the Bible as being blind, but rather a trust and confidence in something that has been evidentially proven to be trustworthy. 
Second, the Bible commands its readers to pursue responsible thinking and discards any notion of easy believe-ism or childish beliefs. As the Apostle Paul says, "Brothers, do not be children in your thinking. Be infants in evil, but in your thinking be mature" (1 Corinthians 14:20).
One of the top Christian thinkers and apologists of the 20th century — Francis Schaeffer — put it like this, "It is unbiblical for anyone to say, 'just believe.'" 
So, without a doubt (pun intended), while a doubting Christian isn't the best Christian in my opinion, a thinking Christian is the best Christian, and I would argue, is the type of believer the Scripture commands us to be.
1. Arndt, W., Danker, F. W., & Bauer, W. (2000). A Greek-English Lexicon of the New Testament and Other Early Christian Literature
(3rd ed., online). Chicago: University of Chicago Press.
2. William Lane Craig, Hard Questions, Real Answers
(Wheaton, Il: Crossway, 2003), pg. 33-4. Emphasis in the original.
3. Danker and Bauer.
4. "Pistis" is the Greek term used in the New Testament for faith, and it means having trust in that which has been shown to be reliable and that which provides a sense of confidence. See "pistis" in Danker and Bauer. Also see Hebrews 11:1.
5. Francis Schaeffer, "The God Who is There" in Trilogy (Wheaton, IL: Crossway Books, 1990), 189.