Ephesians 4:27
...and do not give the devil a foothold.
This book is an example of the infiltration into modern Christian life, we used to call it "new age" beliefs into our churches. The devil has rebranded it "the new spirituality" and has put it into the hands of susceptible Christians to sales numbers of 20 million copies!
Lukewarm pastors, who promote this are seriously harming those who do not read and study their Bibles and pray for discernment.
Do not be lulled into a false sense of security. The devil wants you to compromise your understanding of God. Pray earnestly for protection and deliverance from the wiles of the devil.