God provides His Spirit and gifts each believer. Each believer is trained for ministry in the context of a local church. So, we no longer walk like the Gentiles, or like unbelievers. Unbelievers walk in the futility of their minds, being darkened in their understanding, and are excluded from the life of God because of their ignorance and hardness of heart. To be futile in our minds is to lack understanding concerning the gospel and remain ignorant and hard of heart. It is to live a meaningless life with meaningless thoughts and meaningless motivations that are self-centered rather than moving beyond ourselves.
It is unbelievers, not true Christians, who are callous. Look at how Paul defines callousness—having “given themselves over to sensuality for the practice of every kind of impurity with greediness.” To develop a callous is to have the skin deadened from repeated use. It is good when playing guitar. It is not good in life. We can see the callouses, the deadness, of unbelievers in their treatment of many different issues from abortion to the redefining of marriage. Unbelievers have given themselves over to sensuality and the practice of impurity because of their own greed. Paul takes it back to greed, “My body, my rules.” Greed causes people to be callous and unable to sincerely love others or consider others as more important than themselves; it causes injustice and hatred in society. It is a calloused way to live without much joy and full of bitterness. Christ has provided a better way by His Spirit in the church.
You did not learn Christ in this way. The way of Christ is opposite the way of unbelief. We all once walked in the callousness of our greed. In Christ, we lay aside our old self because it is being corrupted in accordance with the lusts of deceit. Our natural way of life is greedy, but we deceive ourselves into thinking it is not. In Christ, we lay aside our old selves so that we can be renewed, de-calloused, in the spirit of our minds. We put on the new self, which is like God—selfless in the manner of Christ’s sacrifice on Calvary. Our new selves in Christ have been created in the righteousness and holiness of truth. In Christ, we can be free from our greed and all the injustice our greed causes on this earth. Christians are challenged to continually put off the old self and put on the new. Christians are the driving force of sincere, rather than selfish, love on the earth. When there is finally an end to murder, crying, pain, war, unjust discrimination, and so on, it will be because Christians have made disciples of all people, teaching all people to put aside their greed and be rejuvenated in the Spirit.