It's disconcerting when people say, "I don't need to read any other book. I've got the Bible." The reason it's disconcerting is because such a statement and the underlying belief and attitude reveals the arrogance and pride of the person making the statement. To say "I don't need to read any other book but the Bible" is to assume an unrealistic level of knowledge and understanding of the Word of God. Such belief about one's self is to assume a superior level of interpretive skill that even the very best biblical scholars would never assume for themselves.
To say "I don't need to read any other book but the Bible" is to lack humility to a level of taking a gift given by God and giving it back to him while smugly saying, "No thanks. I don't need this." God has given His Church pastors, elders, teachers, and theologians because He loves His Church. Jesus loves His Bride so much that He has provided pastors, elders, teachers, and theologians to assist her in her sanctification and her understanding of His Word.
Sadly, I've known several once-respected men who have gone down the road of "no book but the Bible." They are now Pelagians or they have fallen prey to other heresies.
Make no mistake. The Bible ALONE is the inspired, inerrant, infallible, God-breathed Word of God. Every other literary work is the work of man. But let us all submit to the reality that none of us know the Bible as well as we should. Let us all humbly admit there are pastors, elders, teachers, and theologians who are smarter than we are regarding the great and imperishable truths contained in the Word of God.
Every student needs a teacher. Any student who assumes the role as his sole educator will inevitable stunt his own biblical and spiritual growth.
I thank God for the men--whether layperson, theologian, teacher, elder, or pastor--who have taught me the Word of God over the years. I shudder to think where I would be today if I left the responsibility for my biblical education to no one other than me. I'm glad God has made me smarter than that.