Certainly this is a fair statement of our Roman Catholic friends' confusion over the seeming disarray of Protestant beliefs.
After I read some Van Til I was better equipped to respond to that particular misconception.
If there is a definite, specific, single truth in existence regarding God, then it is right that men search for it, revere it and be led by it.
If we believe men are basically good and it is the world which corrupts, we will stand with Plato and the Greeks who thought the same thing. We then will try to align ourselves with whatever we think is of similar goodness around us to increase the good and lessen the effects of the bad. If we believe in a God, then we assume this is what He wants us to do. Life is then a choice between good and evil, a dualism with the war waging inside of us and outside of us, via God (or any positive force) vs. Satan (or any negative force.)
These assumptions color and effect our faith and our lives to the point where they actually become our faith.
However, if we start from the position of a corrupted nature (due to Adam's Fall), we accept the fact that we must always choose poorly. As Luther wrote, our human will is truly in bondage to sin. If we always choose poorly, we can never please God, and we are lost...unless God actually did decide to save some people by the atonement of His Son's death and resurrection, which is so great a payment as to literally cover the enormous cost of our transgressions.
Now if we believe this scenario of man's total inability to save himself, and Christ's free and complete sacrifice to save those who believe in Him through His mercy alone, then we will approach all of life from this perspective. We will read the Bible and find man's inability and God's regeneration and Christ's redemption and we will find the inward working of the Holy Spirit within our lives.
When this happens, amazingly, we will realize that everything else in our lives that is good and true is coming from this same inerrant source.
The question then becomes why do men reach different conclusions? If we return to Scripture, we find, like Paul and Augustine and Luther and Calvin found, that each man's walk is led by the Holy Spirit. Some are led to faith and some are left in sin.
"But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you." -- John 14:26
And that's just the way it is, all for the glory of God. Basically, a very simple plan, ordained by God from before the foundation of the world. Believe and be saved, by the grace of God alone.
And they of the circumcision which believed were astonished, as many as came with Peter, because that on the Gentiles also was poured out the gift of the Holy Ghost. Can any man forbid water, that these should not be baptized, which have received the Holy Ghost as well as we?" -- Acts 10:44-45,47."While Peter yet spake these words, the Holy Ghost fell on all them which heard the word.
As a Presbyterian, I believe it is the will of the Holy Spirit to work in men's hearts and bring them to faith. As a group, we challenge each other in light of Scripture and keep each other on track. Thus the Westminster, Heidelberg and Belgic Confessions are simply restatements of God-ordained doctrine as reflected from Scripture. The correct writings of men are used by God to further increase our knowledge of Him and our joy in His unmerited gift of Jesus Christ's resurrection on our behalf.
Along those lines, an excellent article is found here:
We are only free to not sin once we have been justified. Then we are truly free indeed as slaves to Christ.