A reader has asked me to elaborate further on the problems with the Protestant doctrine of Sola Scriptura:

1. Protestants like to blame Catholics for promoting non-Biblical, human created, late invented doctrines, but sola Scriptura–on which the entire edifice of Protestantism is based–is a doctrine unheard of until the sixteenth century. It is a doctrine invented by the Reformers and it is a doctrine with no Biblical basis. Ask a Protestant to defend sola Scriptura from Scripture and he can’t. There are a few proof texts that uphold Scripture as ‘profitable for doctrine, reproof etc’ but none teach the doctrine of Scripture alone.
2. Even if you could prove sola Scriptura from Scripture it would be a circular argument. “The Bible is the inspired Word of God and our only authority.” “Where does it say that?” “In the Bible.” “How do you know the Bible is true?” “Because the Bible says it is and we know that the Bible is the inspired Word of God and is true.” “How do you know that?” “Because its in the Bible.” And so on….and on…
3. If sola Scriptura is true and “all you need to do is pray for the Holy Spirit’s guidance and read the clear words of Scripture you will understand” then why are there tens of thousands of Protestant denominations–each of which has prayed for the Holy Spirit to guide them, picked up their Bibles and came to radically different conclusions? Does the Holy Spirit get it wrong?
4. How could sola Scriptura be right when there were so many people down the ages who never had Bibles or couldn’t read? For hundreds of years the first Christians did not have the complete Bible as we have it. For many more hundreds of years people were illiterate and Bibles were expensive and rare. In many other places people did not have the Scriptures in their own tongue. Could it be that God would base salvation on a person’s ability to read, and if not read, to understand the written word? This doctrine was invented with the printing press when suddenly everyone could have a Bible, and without this invention I doubt if anyone would have cooked up sola Scriptura.
5. Catholics teach that the Bible is the inspired Word of God, but that the Church came first. Jesus commanded that a Church be founded, but he never said a word about New Testament being written. The Holy Spirit who inspired and founded the Church also inspires the Scriptures as they are written, preached and studied and expounded. 
6. From earliest days it has been the witness of the Apostolic Church which was the mark of belonging to the Body of Christ. It was the Church from which the New Testament came, the Church which determined the canon of Scripture, and it is the Church which is necessary to set out the proper interpretation of the Scriptures today.
There is plenty of good literature on this, but I recommend my book More Christianity (chapters 1&2) and Mark Shea’s book By What Authority? Most of all read the documents of the Church: esp. Dei Verbum to understand the Catholic teaching.