The kingdom of God is within us when God reigns in us, when the soul in its depths confesses God as its master, and is obedient to Him in all its powers. Then God acts within it as master ‘both to will and to do of his good pleasure’ (Phil. ii. 13). This reign begins as soon as we resolve to serve God in our Lord Jesus Christ, by the grace of the Holy Spirit. Then the Christian hands over to God his consciousness and freedom, which comprises the essential substance of our human life, and God accepts the sacrifice; and in this way the alliance of man with God and God with man is achieved, and the covenant with God, which was severed by the fall and continues to be severed by our willful sins, is re-established. This inner alliance is sealed, confirmed, and given the strength to maintain itself by the power of grace in the divine sacrament of baptism, and for those who have fallen after baptism, in the sacrament of repentance: and afterwards it is constantly strengthened by holy communion. All Christians live thus; and consequently they all bear the kingdom of God within themselves, that is to say they obey God as King and are ruled by God as King.
At this point the zealous man looks inward, and what do you think he finds there? Ceaseless wandering of thoughts, constant onslaughts from the passions, hardness and coldness of heart, obstinacy and disobedience, desire to do everything according to his own will. In a word, he finds everything within himself in a very bad state. And seeing this, his zeal is inflamed, and he now directs strenuous efforts to the development of his inner life, to controlling his thoughts and the dispositions of his heart. From directions on inner spiritual life he discovers the necessity of paying attention to oneself, of watching over the movements of the heart. In order not to admit to anything bad, it is necessary to preserve the remembrance of God. And so he sets to work to achieve this remembrance. But his thoughts can no more be arrested than the wind; his bad feelings and worthless impulses can no more be evaded than the stench of a corpse; his mind, like a wet and frozen bird, cannot rise to the remembrance of God. What is to be done? Be patient, they say, and go on working. Patience and labor are exercised, but all within remains the same. At last someone of experience is found who explains that all is inwardly in disorder because the forces within are divided: mind and heart each go their own way. Mind and heart must be united; then wandering of thoughts will cease, and you will gain a rudder to steer the ship of your soul, a lever by which to set in movement all your inner world. But how can one unite mind and heart? Acquire the habit of praying these words with the mind in the heart, 'Lord Jesus Christ, Son of God, have mercy upon me'. And this prayer, when you learn to perform it properly, or rather when it becomes grafted to the heart, will lead you to the end which you desire. It will unite your mind with your heart, it will cut off your wandering thoughts, and give you the power to govern the movements of your soul.
When a man has been sufficiently illumined, however, to perceive his own faults, he never ceases mourning for himself and for all men, seeing God’s great forbearance and what sins we in our wretchedness have committed and still persist in committing. As a result of this he becomes full of gratitude, not daring to condemn anyone, shamed by the profusion of God’s blessings and the multitude of our sins. Thereupon he joyfully renounces everything in his own will that is counter to God, and he watches over his own senses, so as to prevent them from doing anything beyond what is unavoidably needed.
Dr. George Bebis writes that 'In one of his letters, St. Basil [the Great] explicitly writes that he accepts the intercession of the apostles, prophets and martyrs, and he seeks their prayers to God. (Letter 360) Then, speaking about the Forty Martyrs, who suffered martyrdom for Christ, he emphasizes that they are common friends of the human race, strong ambassadors and collaborators in fervent prayers. (Chapter 8) St. Gregory of Nyssa asks St. Theodore the Martyr... to fervently pray to our Common King, our God, for the country and the people (Encomium to Martyr Theodore).;
Confirm yourself in this truth: that every Divine writing that is in agreement with the path of salvation instructs, teaches, chastises, and strengthens, that our path might be ever according to God.
We ought to learn the virtues through practicing them, not merely through talking about them, so that by acquiring the habit of them we do not forget what is of benefit to us. 'The kingdom of God,' St. Paul says, 'resides not in words but in power' (I Cor. 4:20). For he who tries to discover things through actual practice will come to understand what gain or loss lies in any activity that he pursues.
To more conveniently become accustomed to remembering God, the fervent Christian has a special means, namely, to repeat ceaselessly a brief prayer of two or three words. Mostly this is 'Lord, have mercy.' or 'Lord Jesus Christ, Son of God, have mercy on me, a sinner.' If you have not yet heard of this, then hear it now, and if you have not done it, then begin from this hour to do it.
You have the book of discourses by St. Macarius of Egypt. Kindly read the 19th discourse, concerning a Christian's duty to force himself to do good. There it is written, 'One must force oneself to pray, even if one has no spiritual prayer.' And, 'In such a case, God, seeing that a man earnestly is striving, pushing himself against the will of his heart (that is, his thoughts), He grants him true prayer.' By true prayer, St. Macarius means the undistracted, collected, deep prayer that occurs when the mind stands unswervingly before God. As the mind begins to stand firmly before God, it discovers such sweetness, that it wishes to remain in true prayer forever, desiring nothing more.
Even a pious person is not immune to spiritual sickness if he does not have a wise guide -- either a living person or a spiritual writer. This sickness is called prelest, or spiritual delusion, imagining oneself to be near to God and to the realm of the divine and supernatural. Even zealous ascetics in monasteries are sometimes subject to this delusion, but of course, laymen who are zealous in external struggles (podvigi) undergo it much more frequently. Surpassing their acquaintances in struggles of prayer and fasting, they imagine that they are seers of divine visions, or at least of dreams inspired by grace. In every event of their lives, they see special intentional directions from God or their guardian angel. And then they start imagining that they are God's elect, and often try to foretell the future. The Holy Fathers armed themselves against nothing so fiercely as against this sickness -- prelest.
The root of good inner order is the fear of God. Preserve this fear within you constantly: it will hold everything taut, and will allow no slackness either in physical members or thoughts, creating a vigilant heart and a sober mind, and allowing no bodily torpor or blurring of thought. But one must always remember that success in any aspect of the spiritual life is the fruit of the grace of God. Spiritual life comes entirely from His most Holy Spirit. We have our own spirit but it is void of power. It begins to gain strength only when the grace of God flows in it.
The man who does not humble himself and does not cleanse his heart from evil desires fasts in vain. He may eat nothing at all, but it will be to no avail if there is evil inside him. He must first cleanse himself from the evil within in order to receive the Lord.
If you believe in a Divine Providence which determines the earthly fate of everyone and the way by which he is to be saved, you must also believe that the disposition of your life is the most suitable for you in working out your salvation.
Our prayer reflects our attitude towards God. He who is careless of salvation has a different attitude toward God from him who has abandoned sin and is zealous for virtue but has not yet entered within himself and works for the Lord only outwardly. Finally, he who has entered within and carries the Lord within himself, standing before Him, has yet another attitude. The first man is negligent in prayer, just as he is negligent in life, and he prays in church and at home merely according to the established custom, without attention or feeling. The second man reads many prayers and goes often to church, trying at the same time to keep his attention from wandering and to experience feelings in accordance with the prayers which are read, although he is seldom successful. The third man, wholly concentrated within, stands with his mind before God, and prays to Him in his heart without distraction, without long verbal prayers, even when standing for a long time at prayer in his home or in church.... Every prayer must come from the heart and any other prayer is no prayer at all. Prayer-book prayers, your own prayers and very short prayers, all must issue forth from the heart to God, seen before you.
If the main goal of the repentant sinner should be total, light-bearing and blessed communion with God, then the main hindrance to this is the existence of the passions still active and working in him - the virtues being as yet unsealed in him - and the unrighteousness of his powers. Therefore his main work upon conversion and repentance should be the uprooting of the passions and sealing the virtues - in a word, correcting himself.