[My dad] outlines nine faith wreckers in his book, but I would assert that there is only one faith wrecker (from a purely human perspective); an unwillingness to reevaluate our assumptions. Any of the faith wreckers can be viewed as a variation on this theme. We had a bad church experience so we assume that our view of 'those christians' reflects the Christ they claim to worship. We have experienced horrible, traumatic events in our lives so we assume that God isn't there or doesn't love us. We get lost in ritualistic religion, bewildered at God's apparent departure and assume that it must be something wrong with Christianity itself not with our misconstrued perception of what God desires. These are just examples; in any crisis of faith it is essential to reevaluate our assumptions and reorient ourselves around what we know is true. When I have found myself wandering away from my Savior and Lord I remind myself of all the times God has worked in my life for good. I remind myself of what He declares in His Word. Aren't we all so forgetful, like the Israelites under Moses, and in constant need of a reminder of the presence of the great I AM. We get so caught up in our petty assumptions that we forget what we know is true.
Though there are many things that threaten to steal or erode our faith, Jonathan is right that the "one faith wrecker" is an unwillingness to evaluate or reevaluate our assumptions. I have to ask myself: what assumptions am I holding onto that are false or harmful? What about you?