Garbage in, garbage out – Wikipedia

The term may have been derived from last-in, first-out (LIFO) or first-in, first-out (FIFO).[4]
“Garbage in, gospel out” is a more recent expansion of the acronym. It is a sardonic comment on the tendency to put excessive trust in “computerised” data, and on the propensity for individuals to blindly accept what the computer says. Since the data entered into the computer is then processed by the computer, people who do not understand the processes in question, tend to believe the data they see:

via Garbage in, garbage out – Wikipedia