I had faced the similar issue with my daughter too. She would avoid reading books because of the fear of making mistakes. The trick which worked with her was to show her the progress - now every times she picks a new book, she keeps count of the mistakes and then likes to  read the same book to me again and again till she doesn't make any mistakes.

Believe it or not, there are things you can do to make your son want to read with you! Please take a look at this article, Reading Together: How to Find & Share Books with Your Child, on www.family-homework-answers.com

The answer is simple! HUMOR! Try reading this book together: Sir Farts-A-Lot Hunts the Booger  Look this up and then read..you should be laughing on the floor together by the end of the night

Could you try by working out a deal where you read every other page until he starts getting more comfortable?
Or find stories that he has to just be a certain character. It will improve his confidence and continue to prove to him that he is a great reader.