I didn't need to be convinced that God is a delusion, but it was interesting to follow scientific logic to analyze religion and its inconsistencies. Dawkins builds up the God Hypothesis and my favourite part of the book is then he presents the spectrum of probabilities about the existence of God, ranging from 1 to 7, including for example "Strong Theist", "Impartial Agnostic" all the way to "Strong Atheist".
I considered myself an agnostic but after reading this book I realized I am "De facto Atheist " according to the Dawkins spectrum

"I cannot know for certain but I think God is very improbable, and I live my life on the assumption that he is not there."