In his letter to the Philippians, St. Paul tells us how to live out our salvation in terms that are sobering and startling:
So then, my beloved, obedient as you have always been, not only when I am present but all the more now when I am absent, work out your salvation with fear and trembling.
For God is the one who, for his good purpose, works in you both to desire and to work (Philippians 2:12-13).
This statement stands in stark contrast to a popular misunderstanding of salvation as a single complete act—a sort of bolt of divine lightning that changes us instantly and forever. It also militates against a widespread contemporary tendency to view the issue of salvation in completely rosy terms, minus all those things that are inconsistent with a modern therapeutic mentality—things like hell and fear.
In an important way, Paul’s words also affirm a vital plank of traditional Christian doctrine on salvation—that good works belong to the economy of salvation, that some effort, some element of cooperation on our part is necessary. Listen closely to his words. Paul is surprisingly explicit: work out your salvation. The translation here is an accurate one of the Greek katergazomai, whose root ergon means work and is the source of our words energy and ergonomic.
Of course, the next verse makes an extremely important clarification: For God is the one who, for his good purpose, works in you both to desire and to work.
We work, but it is really God who works through us. Here we have an extraordinary affirmation of the traditional teaching on the relationship between God’s grace and our free will. Here is St. Thomas Aquinas’ brief synopsis in the Summa Theologica:
Free-will is the cause of its own movement, because by his free-will man moves himself to act. But it does not of necessity belong to liberty that what is free should be the first cause of itself, as neither for one thing to be cause of another need it be the first cause. God, therefore, is the first cause, Who moves causes both natural and voluntary. And just as by moving natural causes He does not prevent their acts being natural, so by moving voluntary causes He does not deprive their actions of being voluntary: but rather is He the cause of this very thing in them; for He operates in each thing according to its own nature (Question 83, Article 1, Reply to Objection 3).
The last line is the key to the whole. He operates in each thing according to its own nature. In other words, God moves inanimate things lacking free will according to their nature. The rock falls due to the immutable laws of gravity: it has no choice in the matter. His operation on the rock does not change its nature. Likewise, He operates within us without changing our nature, which includes free will.
This is exactly what Paul seems to be saying (as Aquinas himself points out). He states not just that God works through us, but that he works through us in a way that we too work. And not only that but also his working through us causes us to desire His goodness. That word, desire, is also sometimes translated as will, which is a valid translation of the Greek thelein. (This word may be familiar to some readers in the term Monothelitism, a seventh-century heresy which held that Christ had only one will, thereby denying the fullness of His humanity in what was essentially a throwback to the older Monophysite controversy.)
Paul’s exhortation is set in the context of His majestic hymn to the Incarnation and must be understood in this context, according to Dennis Hamm, SJ, a Catholic biblical commentator. Here is the full text of this well-known and beloved hymn:
Who, though he was in the form of God,
did not regard equality with God something to be grasped.
Rather, he emptied himself,
taking the form of a slave,
coming in human likeness;
and found human in appearance,
he humbled himself,
becoming obedient to death, even death on a cross.
Because of this, God greatly exalted him
and bestowed on him the name
that is above every name,
that at the name of Jesus
every knee should bend,
of those in heaven and on earth and under the earth,
and every tongue confess that
Jesus Christ is Lord,
to the glory of God the Father (Philippians 2:6-11).
Now the mystery of how God works within us while preserving our own free will is recast in light of the mystery of the Incarnation. Sometimes the way the Incarnation is described makes it possible to forget its utterly radical paradoxical meaning. The term Incarnation itself means the taking on of flesh. But Jesus’ humanity was more than a cloak of flesh around His divinity. (That view is close to the heresy of Docetism, by the way.) Being fully human meant having a human soul, intellect, and will co-existing fully with the divine intellect and will.
If God then can become fully human while retaining the fullness of His divinity, then He can certainly move our wills without causing us to losing anything of our humanity—of which the free will is an essential aspect. Of course this remains a mystery, one that is ultimately centered in Christ.
Paul’s hymn to Christ not only illuminates his statement on salvation but gives its further practical weight. In the hymn he depicts Christ’s Incarnational life as an act of obedience that went all the way to the cross. So also, in verse 12, Paul couches our work of salvation as obedience. We can infer, then, that in the same way ‘working’ out our salvation means imitating the example of Christ in assenting to the will of the Father to the point of taking up our crosses (Luke 9:23).
The Incarnational context also illuminates Paul’s somewhat unnerving phrase at the end of verse 13—work out your salvation with fear and trembling. As Hamm points out this is an allusion to an Old Testament phrase for how we should approach the presence of God. As Psalm 2:11 puts it, “Serve the Lord with fear; exult with trembling.” Likewise, Jeremiah 33:9, “They shall fear and tremble because of all the prosperity I give it.”
Now as Christians, we are able to work out our salvation in ‘fear and trembling’ because of the Incarnation, which has made God present to us. He is both present to us through saints like Paul. But He is present even in their absence—working through us in ways most intimate and mysterious, transforming our very will and desire. It is a truth so awesome that we should tremble not only with fear but also with joy even to think of it.