When [Luke] saith that Philip preached Christ, he signifieth that the whole sum of the gospel is contained in Christ. The other speech which he useth shortly after is more perfect; yet it all one in effect. He joineth the kingdom of God and the name of Christ together; but because we obtain this goodness through Christ, to have God to reign in us, and to lead an heavenly life, being renewed into spiritual righteousness, and dead to the world, therefore the preaching of Christ containeth this point also under it. But the sum is this, that Christ doth repair with his grace the world, being destroyed; which cometh to pass when he reconcileth us to the Father. Secondly, when he regenerateth us by his Spirit, that the kingdom of God may be erected in us when Satan is put to flight.
-John Calvin on Acts 8:5.