It had to have taken a while for the word to spread...?

two thousand years ago people didn't have the internet. even if they had a means of m media communication, most of the world was illiterate and probably wouldn't have had any use for it, other than aimlessly looking for . anyhoo, the point of my question is this. when jesus was born, he brought with him a new law to replace the law of the old testament. no more would fathers be allowed to sell their daughters into slavery, no longer would it be ok to kill someone for working on the sabbath, and no longer could parents stone their children to death for being disobedient. however, word of mouth didn't travel quite so fast back then. it must've taken at least a few years for word to get around to everyone about this new law. so, will those who continued to live by old law be punished for doing what they thought god wanted while it was no longer allowed, or will god overlook it because he didn't come up with a better way of spreading his word?