Wow. You just described . . . exactly . . . my old belief system. In fact, it was this form of grace that allowed me to bypass ALL scripture that dealt with submission, obedience, and sharing the Gospel (which is good that I didn't really do it, because I was clueless) . . . and like you said, that form of Grace allowed me to be a hardcore alcoholic, strip-clubber, porn-addicted, sailor-swearing and overall piece of crap citizen. Yet incredibly, I taught and believed that . . . "Nothing can separate me from the Love of God! I'm Eternally Saved regardless of what I do, say, or think!"
While on my continual hunt for additional women to "engage" with, and when the matter of Christianity would arise and they'd ask if I believe in sex before marriage, I taught them that even though it was sin, Christ died and paid for those sins. Incredibly, many "christian" women fell to my former sexual prowess. Unbelievable. I was truly one sick dude.