In the first volume of his Reformed Dogmatics, the great Dutch theologian Herman Bavinck says this:

The essence of the Christian religion consists in the reality that the creation of the Father, ruined by sin, is restored in the death of the Son of God, and re-created by the grace of the Spirit into a kingdom of God (112).

That is one seriously loaded statement. But it lays down the sort of holistic understanding of Christianity that we so desperately need.