As far as reading non-biblical writings, the doves writings are a modern day Enoch or Josephus.  They are not biblical, but they are biblically based and have value.  There are many Christian books and commentaries that can be very helpful in our walk with Christ.  Reading Charles Dobson’s views on the book of Romans, is not the same as reading the bible, but it would be helpful in understanding it.  It is the same with the writings of old.  As long as the writings are biblically supported and not distorted truths, they can be helpful.  We must; however, always base our faith on God’s word and when there is a discrepancy we trust God’s word, and there is no substitute for reading the word of God.  Anytime we study things about God and Christ we only strengthen our walk with him, and can often provide insight into the things we don’t understand. God wants us to search and question and look for the truths because he knows that HE holds all the answers, and our search will lead to him.