I am sure that a work done by one or two pious men is not done without the cooperation of the Holy Spirit. For when nothing merely human is put before us, when holy men are moved to action with no thought of their own personal gratification, and with the sole object of pleasing God, it is plain that it is the Lord Who is directing their hearts.
St. Basil the Great
But there is a second kind of faith, which is bestowed by Christ as a gift of grace. For to one is given through the Spirit the word of wisdom, and to another the word of knowledge according to the same Spirit: to another faith, by the same Spirit, and to another gifts of healing?. This faith then which is given of grace from the Spirit is not merely doctrinal, but also worketh things above man?s power. For whosoever hath this faith, shall say to this mountain, Remove hence to yonder place, and it shall remove?. For whenever any one shall say this in faith, believing that it cometh to pass, and shall not doubt in his heart, then receiveth he the grace.
St. Cyril Archbishop of Jerusalem
Catechetical Lectures. Lecture V
The Lord says, ?Why call ye Me Lord, Lord, and do not the things which I say to you? ?? For men of this stamp do indeed say that they believe in the Father and the Son, but they never meditate as they should upon the things of God, neither are they adorned with works of righteousness; but, as I have already observed, they have adopted the lives of swine and of dogs, giving themselves over to filthiness, to gluttony, and recklessness of all sorts. Justly, therefore, did the apostle call all such ?carnal? and ?animal,???[all those, namely], who through their own unbelief and luxury do not receive the Divine Spirit, and in their various phases cast out from themselves the life-giving Word, and walk stupidly after their own lusts: the prophets, too, spake of them as beasts of burden and wild beasts; custom likewise has viewed them in the light of cattle and irrational creatures; and the law has pronounced them unclean.
Irenaeus Against Heresies, Book V, Chapter VIII
Yet it is in our power, if we will, no longer to be in the flesh, no, nor upon the earth, but in heaven, and in the Spirit. For our being here or there, is not determined so much by our position, as by our disposition. ... Let us then be in ourselves, in heaven, in the Spirit. Let us abide in the peace and in the grace of God, that we may be set at liberty from all the things of the flesh, and may be able to attain to those good things which are promised in Jesus Christ our Lord, with whom to the Father, together with the Holy Spirit, be glory, and might, and honor, now and henceforth, and for ever and ever. Amen.
St. John Chrysostom
Homilies on the Epistle of St. Paul to the Ephesians, Homily V
The point is, as you know, the zeal that we were discussion, that active, live, fervent, untiring zeal that is the sign our spirit has been rehabilitated and restored to its former power through reunion with God by means of the grace and action of the Holy Spirit. We do have outbursts of zeal, but they are only outbursts, and then they are extinguished. The zeal which is always fervent constant and untiring zeal, exists only when our spirit is filled with grace by the Holy Spirit.
St. Theophan the recluse
The Spiritual Life, (p. 116)