A recent Evonomics article makes clear that income inequality is bad for society generally, which is borne out by studies indicating that health outcomes are worse even for the rich in countries with greater wealth inequality.
There are also studies indicating that being rich makes you less altruistic and more self-centered.
Jesus, of course, told the rich young man that he should sell all he had and give the money to the poor: Mark 10 has the story.
17 And as he was setting out on his journey, a man ran up and knelt before him and asked him, “Good Teacher, what must I do to inherit eternal life?” 18 And Jesus said to him, “Why do you call me good? No one is good except God alone. 19 You know the commandments: ‘Do not murder, Do not commit adultery, Do not steal, Do not bear false witness, Do not defraud, Honor your father and mother.’” 20 And he said to him, “Teacher, all these I have kept from my youth.” 21 And Jesus, looking at him, loved him, and said to him, “You lack one thing: go, sell all that you have and give to the poor, and you will have treasure in heaven; and come, follow me.” 22 Disheartened by the saying, he went away sorrowful, for he had great possessions.
23 And Jesus looked around and said to his disciples, “How difficult it will be for those who have wealth to enter the kingdom of God!” 24 And the disciples were amazed at his words. But Jesus said to them again, “Children, how difficult it is[a] to enter the kingdom of God! 25 It is easier for a camel to go through the eye of a needle than for a rich person to enter the kingdom of God.”
So, my libertarian friend, you tell me that for the state to tax you is theft? I suggest that it is doing you a favour – it will bring you at least slightly closer to heaven, according to Jesus (and I have no doubt that, like the rich young man, you wouldn’t feel able to do this for yourself), it will make you a nicer person and improve your health.