Break out the pitchforks and tar and feathers for what I'm about to say.....

Soap will not turn your cast iron into a pile of rust and disappear into oblivion. Soap will not strip off the precious seasoning.

Oil is not "Seasoning".

Oil is used in the creation of the seasoning.

Soap can be used in the cleaning of cast iron. I usually just use hot water and a dish brush, but there are times when soap came in handy.

All followed up with a heated dry, application of an oil, and then a heat to smoke.