`The kingdom of God is within us,' that is, on our lips and in
our hearts. [Luke 17:21] Therefore anyone who prays that the kingdom of
God may not delay its coming is praying that it may be consolidated, extended,
and reach its fullness within him.
Our Lord in fact dwells in all holy people who recognize God as their king and obey his spiritual laws. The Father is present in the perfect soul and Christ reigns together with the Father, according to his own actual word `If someone loves me ... we will come to him and make our home with him.' [John 14:23]
The kingdom will not reach its fullness in each of us until wisdom and the other virtues are perfected in us. Perfection is reached at the end of a journey, so we ought to be `forgetting what lies behind and straining forward to what lies ahead.' [Phil. 3:13)
In other words, on the one hand the believer is a tireless traveler and on the other hand the kingdom of God will reach its completion in us only when the words of the Apostle are fulfilled: `When he has subjected all things, Christ will deliver up the kingdom to the Father, that God may be all in all.' [cf.1 Cor.15:24-28]
Let us subdue our members to produce the fruits of the Spirit. Then the Lord will walk with us as in a spiritual paradise. He alone will reign in us, together with Christ. And we shall already possess the benefits of the new birth and of the resurrection.
[Breviario Patristico © 1971 Piero Gribaudi
Editore, Turin, Italy; translated by Paul Drake]