So having read the article, I have to say the fellow makes many good points. However, few of them are valid in light of the end result.
My Church of 800 did the 40 days along with 15 or 20 other churches in my community. Effect number one: The body was brought together. I guess some purists would say this is a bad thing.
Effect number two: We saw 80 people come to Christ in our church alone as a result of the 40 days. I guess leading people to Christ through the idea that God has a purpose and a plan is unbiblical to some. Personally I have never favored the fire insurance approach to salvation. The love of God approach is what works for most. Yes, maybe a few need to scared into the kingdom.
The third effect was that most Christians find this book to be a reminder of Gods love and power and purpose. It is a refreshing and renewing experience.
So as I said in an earlier post there is always somebody who wont like how you are winning souls, because it is not done the way THEY think is right.
Luke 9:49-50
49 Now John answered and said, Master, we saw someone casting out demons in Your name, and we forbade him because he does not follow with us.
50 But Jesus said to him, Do not forbid him, for he who is not against us is on our side.
For what it is, the 40 days is a good thing. It is not the Bible. It is just a book that many find helpful.