Losing my place in heaven?

A local church's "wayside pulpit" notice board has the following message:

"What if... you doubt God exists? Don't let doubt lose your place in heaven"

As a Christian I find this message profoundly offensive on several levels.  First, it is a message of fear.  To me it is the ultimate backfiring of Protestant religion.  One aspect of the Protestant Reformation was that it sought to remove a climate of fear based on having to behave in a certain way.  By recognizing that we are sinners, asking God's forgiveness in the sincere belief that Christ died to take the punishment upon himself, we can be redeemed.  In shorthand, "all you have to do is believe, and everything will follow from that".  There is no condemnation for those who believe.  And perhaps part of the Protestant appeal to reason is that if belief gets you to heaven, then lack of it will lose you your place in heaven.  But as a message to passers by?  Surely "doubt and you'll go to hell" is no more enlightened than "sin and you'll go to hell".

The second thing wrong with the message is that confusion about what doubt is.  It is being taken as the opposite of belief.  But doubt is a necessary part of belief!  Without doubt, you would have certainty, which is not the same as belief.  Certainty seems to me to be a tremendously damaging force in religion.  Suicide bombers are driven by certainty about their place in heaven.  But the rest of us, however faithful we may be, do not know.  Even this church's own website says "The truthful answer is that we cannot know for certain [that there is a God]"

The third problem for me is the level of certainty that this poster has not only in the existence of God but also in the existence of heaven, with "places" that could be denied to us like seats in a concert hall (would my place be given to someone else, I wonder?)  We really don't know what heaven is.  My understanding comes from Jesus' Sermon on the Mount, where he gives several pictures of the kingdom of heaven, and to me those pictures are so earth-based that there is no need for pie in the sky.  So ironically I end up having nothing to fear from the fearsome message of this church banner.  But I still find it offensive.  I say "keep those doubts flowing".