That sounds like a very simplistic view, Twiglets (I am sure I can remember being told things as a child like "If you say a bad word Jesus will hear you and be cross with you") and a slightly 'hell-fire and damnation' one (as in "be good or you'll be damned to hell for all eternity... so nerrrr").
I believe that the desire to be good (that is, to behave in a way that does not harm others, that helps them where possible, that doesn't further one's own interests at the expense of those of others) is a fundamental human impulse (though one on which at times we all fall down, of course); and it's clear that Christians don't have a monopoly on being this (think of Aristotle's Ethics for instance). For me, however, being a Christian adds an additional level to this which feeds into my understanding of how I relate to the world and to people in it. I understand divine creation to mean that God is here in the world and in the people that He made, and this means that my relationship with the world and with other people is all an extension of my relationship with God. Jesus said that the way in which we treat other people is also the way in which we treat Him ("whatever you did for one of the least of these brothers and sisters of mine, you did for me"). He also told us that the greatest commandments, to which all the others can be reduced, are (a) to love God, and (b) to love our neighbours as ourselves, and importantly He explained that our neighbours are not just our friends and families and those people we like and who are like us, but also those people whom society excludes, people who are not like us, people we find 'difficult', even people who harm us.
Believing this, doesn't make me a better person necessarily (I wish!), but it does give me a model for goodness and an impetus to do good which help me in my attempt to be a decent person. And when I am tempted to be selfish or greedy or whatever, it reminds me that there is another (better) way. I am reminded of the old hymn, "My God, I love thee not because...", which ends: "not with the hope of gaining aught, / not seeking a reward; / but as thyself hast loved me, / O ever loving Lord! / So would I love thee, dearest Lord, / and in thy praise will sing, / solely because thou art my God / and my most loving King". As this hymn says, I don't try to behave well because I want to get something in return for my good behaviour, and nor do I try to behave well because I am afraid of what will happen to me if I don't (which seems to be your relative's position), but because my model and my inspiration for doing good is so inspiring, so worthy of love, so... I can't think of the right word, I want to say "noble", which is an old-fashioned word, but kind of sums up the sort of goodness that I am thinking of, that to try to emulate Him is a pleasure and a joy rather than a duty or something done out of fear.
I fear I'm not explaining myself very well, but that would be my take on this, anyway...