I am sticking with what Peter said ~ Growing in the Spirit (2 Peter 1:5-10).
Those who can grow in the Spirit could only be those who were born of the Spirit.
"First clean the inside of the cup and dish, and then the outside also will be clean." Matthew 23:26
You're not really changing on the inside if you're not changing on the outside. Ultimately, you can't separate the two as you are trying to do.
We see people, both Christian and non-Christian, doing works which appears good and righteous. Feeding the hungry, giving aid to victims of flood, of fire, of war, etc. Yet we know that not all of them could have been born of the Spirit. So then, it could not be by works nor by doing works.
Looking at works and the man (oneself) is an old covenant mind. Looking at the Spirit and Jesus Christ is the new covenant mind.
7Little children,d let no one deceive you: The one who practices righteousness is righteous, just as Christ is righteous.e 8The one who practices sin is of the devil... 1 John 3:7-8
Don't throw away John's words just because you know of an atheist that's more kind to the poor than most Christians. You need to broaden your view of what righteous works looks like in a person's life. It includes the manifestations of
all of the fruit of the Spirit, not just kindness or mercy, for example. Being righteous as He is righteous also means being a patient person, a forgiving person, a faithful person, a gentle person, a self controlled person. Works of righteousness, all of which are visible to the naked eye.
These unbelievers who can be generous in times of need are the same soulless creeps who can otherwise be so greedy, and hateful, and immoral as a matter of lifestyle. They do not lead lives of righteousness just because they give to charity. The righteous life includes a lot more than that. And, you'll notice in scripture that the love Christians have is especially noteworthy in regard to the
people of God. Unbelievers are not very sympathetic and loving to the church, that's for sure.