Christians will sometimes say that non-Christians are not capable of performing good actions. Their reasoning is that because non-Christians are still subject to the effects of the Fall (incorrectly assuming that Christians are not) and do not have the Holy Spirit, it is not possible for them to do anything good.
This is a very arrogant position
Essentially, it is saying that every single action that non-Christians perform is self-motivated, and Christians are the only ones who can have right motivations. Besides being arrogant, I think this is demonstrably false.
I was talking with a non-Christian friend of mine about this, and he suggested that he performed an altruistic act that had absolutely no self-motivation behind it.
He was with his friend at his fraternity house, and he wanted a cookie. So, he got up and got a cookie and brought one back for his friend (thinking that he might also want a cookie). There was no self-motivation, no hope that his friend would get him a cookie later, or any hope of being paid back in any way. This seems like a generally selfless act, right?
For the Christian to say that only Christians can do good things, this act of getting a cookie for one’s friend had to be somehow, at some fundamental level, evil. I think common sense tells us otherwise.
I think this position is scripturally incorrect
I have seen many passages of scripture that warn us about the evilness of fallen humanity. However, I am not aware of any passages that say it is impossible to do anything good without being a Christian. In fact, Scripture says the contrary.
“For when the Gentiles, who do not have the law, by nature do what the law requires, they are a law to themselves, even though they do not have the law. They show that the work of the law is written on their hearts, while their conscience also bears witness, and their conflicting thoughts accuse or even excuse them” (Rom 2.14-15, ESV, italics added).
The Gentiles’ consciences bear witness to their actions and either accuse or defend them. To accuse them means they’re guilty, but if that’s true, then wouldn’t their conscience defending their actions mean that they did something right?
Christianity is not about suddenly being able to do nice things for other people
On Christianity, man was originally created good. After the Fall, we all became mixed creatures - each of us has bits of good and bad in us. Part of what Christianity is about is renewing us into who we were meant to be. However, that does not happen instantly, nor does that mean that everyone else is completely bad.