We are seeing the extremes in the argument stated here. We have:
A). Those that resist knowledge thinking that there is something spiritual and virtuous in "simplicity." This is the hinge-pin of their "theology."
B). There are some I am sure that have a lot of knowledge. Perhaps never being saved, yet going through Bible College and graduating to teaching the bible and theology without any personal experience.
Those are our extremes: I have met people more in the middle:
A). Saying that we should stick to the "simple" basic Gospel and not make it difficult.
B). Saying that a Christian should have a hunger to know the True God, to know the truth about what He teaches, and to study to show ourselves approved.
The simplicity of the Gospel is definitely necessary. We are called to preach the Gospel! I do not know many so-called "Intellectuals" that would deny it... but, what exactly is the "Gospel"? Is it really all that "simple"? Look through the Forum and you will find that this is not as simple of an answer as you would want! Personally, I have known a few "anti-intellectuals" (those that demand simplicity) that rebuked me because I said something which went against what they believed. They got "saved," and that is all they needed! It "works for them" so don't throw any Biblical facts into the mix and mess it up! Do not tell them anything that might question the accuracy of what they may believe!
True belief has some good and bad characteristics. If you truly believe something, your life is changed by it. You make changes in your life based upon that belief. The tendency is to never question what you believe. You buy books that affirm, not question what you believe. You gravitate to preachers who will tickle your ears and confirm your bias. Why not? What you believe is the Truth!
So, if someone comes along after a few years, and throws valid Biblical facts at you, and these truths question or alter your current belief; it is crushing! You can either accept and change; or reject and stay in your comfort zone. Most people resist changing because they would have to admit to people that they were wrong (pride), and if the change is deep enough, they may even have to scrap the entire belief system they had for something new! This is asking a lot! For many, to change to reconcile your life to the facts is too high of a cost.
"But I fear, lest somehow, as the serpent deceived Eve by his craftiness, so your minds may be corrupted from the simplicity that is in Christ. For if he who comes preaches another Jesus whom we have not preached, or if you receive a different spirit which you have not received, or a different gospel which you have not accepted-- you may well put up with it." 2 Cor. 11:3-4.
When we look at the extremes at both ends, Paul gives us something that puts us closer to the middle.
At first glance it looks like Paul is saying that we should not go beyond the simple. But reading further we see that what he writes is not all that simple! Yes! What is needed for someone to step into the light, to get "saved" should be simple! But God is not done with that person after their conversion.
"Another Jesus..." One does not have to go far in this world to realize that there are many different kinds of "Jesus," and they are not the "same" Jesus! Is he God? Just a good Teacher? A Prophet? A good Man? Do you have the Real Jesus?
Does it matter? Yes! Paul says it does! If you have the wrong Jesus, you are worshipping an Idol. How do you know? Is this "simple"?
"A different spirit..." There are many that claim that the Spirit leads them into all truth, and what the Bible says does not matter. the problem is, no two people "led by the Spirit" have the same understanding and "Truth" as the other one! How do we know... is it that "simple"? If it were not for what the Scriptures teach, how else would we know if someone is listening to the Holy Spirit and not "another spirit"?
"A different gospel..." Clearly, this is in debate every day on the Forum! How do you know if you have the right "Gospel," and not a "Different Gospel"? Just because yours "works for you" is no proof, because everyone that disagrees with you has a "Gospel" that "works for them!" If we did not look at Scripture and go beyond "simplicity," or study to know what Scripture says, how can we be assured that what we believe is an accurate "Gospel" or "another gospel"?
Paul writes both sides of the truth; there is the "essential" Gospel, and there is the intellectual work of being aligned with truth. Once someone is "saved," then God expects growth.
This is just breaking down the difference between true believers and false teachers. It is the difference between a Babe in Christ, and a Mature Christian. Between milk, and meat. Something is wrong if a Believer only wants milk! This is fine if they have not been a Believer very long, but when it becomes a passionate Theory not to advance, it becomes a problem.
Anyone that thinks that you must believe their entire theological system to be "saved," is preaching "another gospel." This does not mean that their "system" is wrong, but that God has kept the Gospel simple. It is not intellectual assent to truths that saves us, but trust in the work and Person of Jesus Christ on the Cross to save us.