Being a “good” person — real or an illusion?

I was born into a Christian family and a Christian society. I know people who were born into all kinds of religions. All say that the most important value or goal in their belief systems is being a good person, some just trying to be so in general while others performing certain actions like giving to charity, volunteering etc. I think most of us — more or less compassionate humans — will agree that helping others either regularly or occasionally feels good. It can make us feel useful and joyful when we see an improvement in someone’s life or day due to our assistance.