IT’S NOT GOOD TO OPERATE ON CREDIT

The following text is from the book I am reading "Art and Advertising by Joan Gibbons".

But how can the highlighted sentences be some "truths"? I think it is only possible, if they are understood as irony, that is "every body knows that CRIME AGAINST PROPERTY IS very IMPORTANT, GUILT AND SELF LACERATION ARE not INDULGENCES, and IT is GOOD TO OPERATE ON CREDIT". What do you think?

And what does it actually mean "TO OPERATE ON CREDIT"? Does it mean to trust the credit of others"?

Context:

For de Gourmont, the banality of the commonplace becomes its redeeming feature, allowing for the expression of the sort of basic everyday truths that people depend on in the way that they depend on bread and wine for sustenance. Holzer’s Truisms provides a clear example of the way in which the commonplace is used to do exactly this, succinctly presenting what appear to be banal and simple truths that, in effect, refer the reader on to larger and more abstract chains of thought:

ABUSE OF POWER COMES AS NO SURPRISE
A LITTLE KNOWLEDGE GOES A LONG WAY
BEING HAPPY IS MORE IMPORTANT THAN ANYTHING ELSE
BEING JUDGMENTAL IS A SIGN OF LIFE

CRIME AGAINST PROPERTY IS RELATIVELY UNIMPORTANT

GUILT AND SELF LACERATION ARE INDULGENCES
HUMANISM IS OBSOLETE
IT’S NOT GOOD TO OPERATE ON CREDIT
LACK OF CHARISMA CAN BE FATAL
SALVATION CAN’T BE BOUGHT AND SOLD
YOU ARE A VICTIM OF THE RULES YOU LIVE BY