“…the righteous judgment of God, who WILL RENDER TO EACH PERSON ACCORDING TO HIS DEEDS: to those who by perseverance in doing good seek for glory and honor and immortality, eternal life; but to those who are selfishly ambitious and do not obey the truth, but obey unrighteousness, wrath and indignation.”– Roman 2:5b-8, New American Standard trans.
I would hazard that “doing good” means just that. With Jesus as our example we lay down our lives for others, setting aside our ambitions and wants for the needs of others that are all around us. We help widows and orphans, we give to “the least of these” and seek peace in a world of constant war and oppression. I believe it also means that we forgive seventy times seven, turn the other cheek, go another mile. We do good by living out the kingdom of God in our daily actions.
Then he will say to those on his left, “Depart from me, you who are cursed, into the eternal fire prepared for the devil and his angels. For I was hungry and you gave me nothing to eat, I was thirsty and you gave me nothing to drink, I was a stranger and you did not invite me in, I needed clothes and you did not clothe me, I was sick and in prison and you did not look after me.” They also will answer, “Lord, when did we see you hungry or thirsty or a stranger or needing clothes or sick or in prison, and did not help you?” He will reply, “I tell you the truth, whatever you did not do for one of the least of these, you did not do for me.” Then they will go away to eternal punishment, but the righteous to eternal life.– Matthew 25:41-46, New American Standard trans.