Just imagine Christianity would finally end and Ray Comfort would have to find a real job.
Perhaps he just fights so hard for Christianity to continue because he does not know what would become out of him in such a world.
Some suggestions:
Door-to-door salesmen with his favorite slogan:
"Buy this product or burn in hell."
Or he might open a shop for fruits and vegetables explaining to women what bananas are also perfectly shaped for....

maybe you have some more ideas what could become out of him...