It's just a common expression for 'do the morally right thing' under the theory that Jesus was perfect. Obviously on reddit it's kinda sarcastic. Anyway put the Jesus thing aside. Jesus is often not discussed with great solemnity.

The point is that MPRE 'correct' answers, on questions you don't know the answer to, are often not the morally best answer. They are between the obviously awful answer and the obviously moral answer.

It really sucks for you that the bar exam was moved to September, leapfroging your MPRE. Don't overprepare for the MPRE. What are your scores on the free tests (themis and barbri)? You might not need as much prep as you think.