How can God's love and humanity's selfishness be brought together in a communing fellowship?

Since the selfish sinner is unwilling, and unable to become willing, to participate in a fellowship or communion of love with God and other human beings, why has God not abandoned humans completely? Christianity answers that since God is ultimate and humans are finally accountable to God, and since the reality of God is a love that wills to commune with humans right now as well as forever afterward, God is not indifferent to humanity's unwillingness to love and to be loved rather than to be a self. Because the reality of God in Christ is the love that aims for communion, that love cares whether humans accept or reject it. It would cease to be righteous selfless love if it relented in its will to create communion with those who have rejected it. Because it does continue to care infinitely for those who are unwilling to commune with it, God's love requires that humanity's estrangement be overcome and that a radical atonement be established between loving God and selfish humanity.

How can God's love and humanity's selfishness be brought together in a communing fellowship? Christianity asserts that this is a question for God to answer, because humanity is in no disposition to renounce and sacrifice anything of its own. Therefore, the motivation, the will, and the resources to atone holy (loving) God and unholy (selfish) humanity are all on God's side. This situation, according to Christianity, constitutes the crisis point at which grace, the inexplicable extension of God's love, becomes necessary. It supplies the missing link between God's love and humanity's selfishness that is necessary for the salvation of humankind from the sinful, fallen condition.

At the same time, Christian teaching maintains that the mere presence of God's love does not suffice to induce selfishness to yield itself to communion with God's love. The power of God's love has to be conducted in such a manner that it creates communion with selfish people while they are still being selfish. Christians are instructed to see God's love demonstrated in precisely that creative manner in Jesus Christ, and they refer to it as "the grace of God given in Jesus Christ." What they see in Jesus Christ and call grace is God's making a sacrifice that humans ought to have made but refused to make. Christianity announces that right here in human history - where humans ought to have sacrificed their selfishness to God - the love of God acted vicariously for humanity in Jesus Christ and sacrificed selfless love to selfish humanity. This grace, this vicarious action of God's love, has supplied the missing link, in Christianity's scheme of salvation, a link that has joined holy (loving) God and sinful (selfish) humans in a radical atonement:

'In Christ God was reconciling the world to God's reality, no longer holding humanity's transgressions against them . . . . Christ was innocent of sin, but for our sake God made him one with our sinfulness so that in him we might be made one with God's goodness' (2 Corinthians 5:19, 21).