The concept of child-like faith, in evangelical circles, seems to be taught in such a way that we should have child-like faith and not question too much. Instead, blind faith is sufficient. Just like a child does not know a lot but just blindly trust parents and those in authority, so we should not be too critical and instead just accept all that our pastors teach us. The sheep are then focused on "practical applications", while eschewing doctrinal truth which are meant for "theologians", a supposed ultra-elite class of super-Christians who are near infallible in their doctrinal pronouncements, functioning as the de facto mediator between Christ and the laity.
Of course, the Scriptures teach nothing of that sort — a fiction which is sadly prevalent in many authoritarian societies (especially in Asia) where those in authority are respected almost to the point of unquestioning obeisance. So what exactly is this child-like faith as taught in Scripture?
“At that time the disciples came to Jesus, saying, “Who is the greatest in the kingdom of heaven?” And calling to him a child, he put him in the midst of them and said, “Truly, I say to you, unless you turn and become like children, you will never enter the kingdom of heaven. Whoever humbles himself like this child is the greatest in the kingdom of heaven” (Matthew 18:1-4)
In this passage, the main quality highlighted by Jesus is that of humility, as stated in v4. To become like children or to have child-like faith in this context means to be as humble as children. While of course there are proud children in this world, the focus is on the nature of young children in general. Young children trust their parents' word as truth, and act upon it as such. They do not think that they know it all, but rather admit what they do not know and fall back on their parents.
In the same way, the essence of child-like faith is humility before God. Humility before God means trusting in Him and obeying His Word, not questioning it and rebelling against it. Instead of thinking that we know what is best, we should submit to God and His Word even when it doesn't make sense at the moment.
Child-like faith implies humility before God's Word. With regards to knowledge, child-like faith means that the believer holds to God's Word as true even though Scripture is being attacked by many unbelievers some of whom may even be within the churches. Christians take God's Word as the axiom of all of life, knowing that regardless of what men say, 'Let God be true though every one were a liar'
Romans 3:4 - “Let God be true though every one were a liar, as it is written, “That you may be justified in your words, and prevail when you are judged.”Instead of promoting anti-intellectualism therefore, the essence of child-like faith is not ignorance but rather humility before God in using His Word as the basis of our knowledge. Child-likeness therefore relates to the attitude which we bring to God's Word and the foundation of our knowledge rather than the quality or quantity of knowledge gained. Far from discouraging knowledge, child-likeness is the godly attitude for the building up of true knowledge of God, of Man and of the world. Such would yield good fruit that conforms with true godliness and salvation.
In this light, to cause "one of these little ones" to sin as stated in v6 is indeed a terrible thing. Since the essence of child-like faith is humility before God and His Word, the sin in verse 6 is to question God's Word and undermine its authority. Higher criticism, Liberalism and Neo-Orthodoxy all destroy or gut the Word of God of its authority in the lives of believers. By making the thoughts and prejudices of men the arbiter of which Scripture is inspired (i.e.. inerrant, infallible in every jot and tittle) and which are not, such "scholarship" destroys child-like faith in those who accept and believe them. For those who propagate such doctrines of demons, it would be better for them to have great millstones thrown around their necks and to be drowned in the sea (Matthew 18:6).
In conclusion, child-like faith is not what many have made it out to be. It is humility before God and His Word, and nowhere inimical to growth in knowledge but rather the only godly basis for growth in true knowledge.