The book is a rallying cry to Christians everywhere to go the extra mile for God and mankind.
In an age of me, myself and I, Chan challenges Christians to buck the trend and really "love your neighbour as yourself".
The book as not left the New York Times Best Sellers list for the last 83 weeks.
Responding to news of the sales, Chan said: "I'm amazed by the book's popularity. But if it doesn't lead to concrete action in the readers' lives, then it was just another book. I pray that it has caused us to truly fall more in love with the One who deserves our best."
"Crazy Love" isn't just something Chan has written about. It's something he strives to do in his life. He shocked everyone a few years back when he and his family left Cornerstone, the growing church he founded, in order to serve in the low-income Tenderloin district of San Francisco.
His is striving to demonstrate the love of Jesus to the neighbourhood in practical ways and plant a church in every apartment building in the district.
The ministry offers meals, clothes, school supplies, and anything else that might be needed.
Chan writes "I believe He wants us to love others so much that we go to extremes to help them."
Chan is traveling the world in 2012 continuing to encourage everyone he speaks to, to read the bible, know it and live it. Earlier this year, Chan spoke to over 44,000 university students from around the United States and over 30 other countries at the Passion 2012 Conference in Atlanta.
"I am blown away at the impact that this book has had reaching so many people," said Don Pape, Vice President Trade Publishing at David C Cook.
"Crazy Love embodies David C Cook's mission, to make and teach disciples who obediently transform today's generation. We hope it continues to reach new readers in the coming years changing lives forever."
Chan's latest release, "Multiply", is out on 1 November.