Charles Spurgeon Commentary Matthew 12:28

"But if I by the Spirit of God cast out demons, then is the kingdom of God come upon you." — Matthew 12:28 (ASV)

Our Lord, in effect, says: If I cast out demons by the Spirit of God, then a new era has begun. The divine power has come into distinct conflict with the evil one and is clearly victorious. In My Person is "the kingdom of God" inaugurated, and you are placed in a position of gracious advantage by My presence among you. But if the demons are not cast out by the Spirit of God, the throne of God is not among you, and you are grievous losers.

The overthrow of evil is a clear proof that the kingdom of grace has come. Note that, though our Lord had power all His own, He honored the Spirit of God and worked by His energy, and mentioned the fact that He did so. What can we do without that Spirit? Lord God the Holy Spirit, teach us to wait on You!