I've noticed something about people who describe themselves as "good" or "nice." This is, of course, a generalisation, but one that, in my experience, is very often true. What I've noticed is that when people call themselves good or nice, they are looking at the most devastating forms of evil and cruelty that they can comprehend, seeing an absence of that behaviour in themselves, and using that as evidence that they are, as they say, good or nice.
"I don't rape, torture or murder, so I'm a good person."
"I don't beat up women or say rude things all the time, so I'm a nice guy."
Before I became a Christian, I was the same. I was good and nice because of all the bad stuff I didn't do (and also in spite of the bad stuff I did do, which there was plenty of for me to ignore). But if that's how we define good or nice, then we aren't making a positive statement with that claim, we're making a negative statement. We aren't asserting anything that we are, we're only dismissing what we're not (or what we'd like to think we're not).
Let's be clear. Outside of morality, "good" implies positive function, not just the absence of dysfunction. When we use "good" as a moral stance, we elevate that above the amoral meaning of good, and so the moral definition of good becomes the positive presence of moral values and virtues, not just the absence of vices. Likewise, while "nice" doesn't carry as much power as good (and it isn't always nice to be good, nor is it always good to be nice), when we aren't applying the term to ourselves, nice generally means pleasant. A nice flavour is one that brings us pleasure, not just one that doesn't bring us disgust. In the same way, for someone's behaviour to be nice, they actually have to behave in such a way as to enhance the experiences of those around them, not simply avoid hurting people.
As it isn't said nearly often enough: the absence of a thousand vices does not account for a single virtue.
I see this all the time in people who describe themselves as good or nice. They judge themselves by the vices they don't have, rather than looking to virtues. Meanwhile, the people who are living out good morals and nice behaviours are the ones I never hear calling themselves good or nice.