The reason we use oils on the surface of our rifles is to create an impermeable barrier to prevent free oxygen from binding with the metal atoms of the weapon, which would cause corrosion, right? And, when rifles are prepared for painting, all such oils must be stripped from the weapon so that the paint can properlt adhere, correct? My question is: what level of protection against oxidation does the paint provide compared to oils? Less? More?

It's usually pretty good.

I use CLP on my painted surfaces, too. I've even used cosmoline on the paint to change the sheen.

Quoted: My question is: what level of protection against oxidation does the paint provide compared to oils? Less? More?

It depends on the quality and type of paint, the environment it is being used in, and the preparation of the surface the paint is being applied to.

That said, paint should not be used to replace oil for corrosion resistance.