>>33259236 (OP)First establishing what a human being is. If you are a materialist, then a human is no different from an animal, so better means something to the effect of healthier, more adapted. But by better I assume you mean morally better. There's no objective morality in a materialist framework, so there's nothing you can do.
Now Christians believe human beings are rational and moral beings created God's image, but fallen due to original sin. What you do to become a better human being is to imitate Christ as much as possible in order restore the original state of man as God intended.