(Image removed from quote.)
I don't even get it
The joke is that Christianity tends to bring in people swirling the drain and it's opportunistic to suck in people with an ideology that claims you will be not only be saved from the nietzschean hell that is human existence if you have a certain praxis with zero evidence or scientific reasoning behind that claim. Jesus then asserts Yes in the face of a sneering doubter since the idea is to save the wretched of the earth.
I interpreted it as:
Religion, no matter how Godly or divinely ordained, is still made up of people at the end of the day, and the people who need religion the most are in turn some of the worst exploiters of it.
But in a way, this is the system Working As Designed, as a sinless man has no need for salvation.