Church Fathers Commentary Luke 17:20-21

"And being asked by the Pharisees, when the kingdom of God cometh, he answered them and said, The kingdom of God cometh not with observation: neither shall they say, Lo, here! or, There! for lo, the kingdom of God is within you." — Luke 17:20-21 (ASV)

St. Cyril of Alexandria: Because our Savior often spoke of the kingdom of God in His discourses to others, the Pharisees derided Him. This is why the text says, And when he was asked by the Pharisees when the kingdom of God should come. It was as if they were tauntingly saying, "Before this kingdom of God you speak of comes, the death of the cross will be your fate." But our Lord, demonstrating His patience, does not revile when reviled. Instead, precisely because they were evil, He does not return a scornful answer, for the text continues with His words: The kingdom comes not with observation.

It is as if He is saying, "Do not seek to know the time when the kingdom of heaven will be at hand again. For that time can be observed by neither men nor angels, unlike the time of the Incarnation, which was proclaimed by the predictions of the Prophets and the announcements of Angels." Therefore, He adds, Neither shall they say, Lo here! or, Lo there!

Alternatively, they asked about the kingdom of God because, as is said later, they thought that the kingdom of God would be immediately revealed when our Lord came into Jerusalem. Therefore, our Lord answers that the kingdom of God will not come with observation.

Now, it is for the benefit of each individual that He says what follows: For behold the kingdom of God is within you. That is, it rests with you and your own hearts to receive it. For every person who is justified by faith and the grace of God, and is adorned with virtues, can obtain the kingdom of heaven.

Gregory of Nyssa: Or perhaps, the kingdom of God being within us means the joy that is implanted in our hearts by the Holy Spirit. For this joy is, so to speak, the image and pledge of the everlasting joy with which the souls of the saints will rejoice in the world to come.

The Venerable Bede: Or, the kingdom of God means that He Himself is present in their midst—that is, reigning in their hearts by faith.