According to the word of our Lord and Savior, the Kingdom of God does not come observably, nor shall men say “Lo it is here”, or “Lo is it there”, but the Kingdom of God is within us; for the utterance is exceedingly near in our mouth and in our heart.

It is therefore plain that he who prays for the coming of the kingdom of God prays with good reason for rising and fruit bearing and perfecting of God’s kingdom within him.

For every saint is ruled over by God and obeys the Spiritual laws of God, and conducts himself like a well-ordered city.

And the Father is present with him, and Christ rules together with the Father in the perfected Soul, according to the saying that I mentioned shortly before: We will come unto him and make abode with him.

By God’s kingdom I understand the blessed condition of the mind and the settled order of wise reflection;

By Christ’s kingdom I understand the issue of words of salvation to their hearers and the practice of acts of righteousness and the other excellences; for the son of God is word and righteousness.

But every sinner is tyrannized by the ruler of this world, since every sinner is in conformity with the present evil world, and does not yield himself to Him who gave Himself for us sinners that He might release us from the present evil world and release us according to the will of God our Father, as it is expressed in the Epistle to Galatians.

And he who, by reason of deliberate sin is tyrannized by the ruler of this world, is also ruled over by sin: wherefore we are bidden by Paul to be no longer subject to sin that would rule over us, and we are enjoined in these words, Let sin therefore not rule in our mortal body that we should obey its lusts.

Origen Adamantius (c.185-254): On Prayer, ch. 15.