If we are saved by grace, through faith (Eph 2:8), why is an effort of our will required? Our works do not save us, but we cannot be saved without works.
This is a paradox to many, who feel the need to deny the truth of one statement or the other. A full understanding of this mystery comes only with spiritual discernment, but the teachings of the saints can help us attain some measure of understanding.
The following teachings of St. Maximus the Confessor, from his Four Hundred Chapters on Love, provide some help to us.
What anyone loves he surely holds on to, and looks down on everything that hinders his way to it so as not to be deprived of it. And the one who loves God cultivates pure prayer and throws off from himself every passion which hinders him.
The one who sees a trace of hatred in his own heart through any fault at all toward any man whoever he may be makes himself completely foreign to the love of God, because love for God in no way admits to hatred for man.
The one who loves me,' says the Lord, 'will keep my commandments,' and 'this is my commandment, that you love one another.' Therefore the one who does not love his neighbor is not keeping the commandment, and the one who does not keep the commandment is not able to love the Lord.
These texts make it clear than none of us loves God as we ought, as the Lord commands us to. What, then are we to do?
The purpose of the commandments is to make simple the thoughts of things; the purpose of reading and contemplation is to render the mind clear of any matter or form; from this ensues undistracted prayer.
The commandments are given us in order to free us from the need to figure things out ourselves, and to teach us to trust God. Reading and contemplation are given us in order to redirect our mind away from earthly things and toward God. This explains why the best reading is Holy Scripture — the Word of God — and the works of the Holy Fathers are a close second, but worldly writings (even those about religious topics) can even be harmful.
And so works help us grow in the love of God:
"Do not say that 'mere faith in our Lord Jesus Christ can save me.' For this is impossible unless you acquire love for him through works. For in what concerns mere believing, 'even the devils believe and tremble.'
But at the same time, it is a grave error to think that these works save us:
"The one who has not yet obtained divine knowledge activated by love makes a lot of the religious works he performs. But the one who has been deemed worthy to obtain this says with conviction the words which the patriarch Abraham spoke when he was graced with the divine appearance, 'I am but earth and ashes.'"
Works are important as a means of developing in ourselves that love – a practical, all-encompassing love that encompasses our entire being – mind, heart, and will. Works do not save us, but they are necessary because our fallen will fights against accepting that salvation, preferring the love of transitory, earthly things to that of God.
St. Maximus is one of the best known opponents of the Monothelite heresy. This was an imperially sponsored heresy, a "compromise" designed to unite the Christians in the empire in the face of attacks from external enemies.
The monophysite heresy, which was formally rejected at the 4th Ecumenical council in the year 431, stated that Jesus Christ had only nature. His Divine Nature, according to this view, completely assimilated the human nature that He assumed at the Incarnation. The fathers rejected this view. If Christ did not have a complete human nature, they explained, then our human nature has not been saved.
Many people continued to hold on to the monophysite viewpoint during the 5th-6th centuries, so the Byzantine Emperor tried to re-unite the two parties by proposing that Christ had two natures (Divine and human) but only one (Divine) will. This is the monothelite position.
St. Maximus and the Orthodox fathers following him insisted in the importance of Christ's human will — and the active participation of our human will — in the matter of our salvation. We are gifted with free will and must freely choose to love God rather than ourselves, our passions, or the things of this world. Christ fully submitted his human will to the Divine will, as a free choice — and so must we.