I'm impressed that you took the time to read it!  I think the author on page 3 was trying to contrast God's kingdom with worldly kingdoms that rise and fall.  Christianity wasn't first, but its staying power has been strong.  A belief system has to have a foundation or its just an opinion.  For Christians that foundation is the Bible, which we trust is at the very least a morally accurate representation of God's will and his activities on earth in the person of Jesus.  If you don't believe that premise, then I can see why people quoting it would be an annoying and ineffective argument.  Taken in proper context though, you might find it enlightening.  Homeless housing at church- I've read that many with the space have tried and run afoul of local zoning laws.  And consider if it would be harmful to the church buliding's primary mission - being a place of worship, with activities all week not just Sunday.  You will find many Christians at work at your local salvation army