There is lots that can be said on the question of faith and free will. But those who insist faith is synergistic or fundamentally a matter of human choice above all will run into some particular problems. Let me list just three of them.

The problem of spiritual deadness

The first issue facing synergists and free will advocates is that the bible routinely speaks about mankind, by nature, being dead in sin. It alternatively talks about us being slaves to sin. This means that our will does not naturally incline towards what is good nor towards God.

Martin Luther said:

“…man can receive nothing unless given him from above; so that free-will is nothing!” I say that man, before he is renewed into the new creation of the Spirit’s kingdom, does and endeavours nothing to prepare himself for that new creation and kingdom, and when he is re-created has does and endeavors nothing towards his perseverance in that kingdom; but the Spirit alone works both blessings in us, regenerating us, and preserving us when regenerate, without ourselves…” 

As A.W. Pink rightly put it in his book The Sovereignty of God, ‘A dead man is utterly incapable of willing anything’.

If we are dead in our sin, how are we capable to cooperating with God or choosing, of our own volition, to come to God?

The problem of prayer

If we are saved by choosing God through our own free will, we run into a problem of prayer. The theologian and bishop, Augustine of Hippo, frames the problem this way:

In other words, what is the point of praying for God to work in the heart of those we want to be saved if God has no authority over their free will? What, exactly, are we asking him to do? If God cannot turn the souls of men, why bother praying for him to save anybody?

The problem of God’s plans

if we believe that our free will is the primary mover in coming to faith, we create a significant problem for God’s plans coming to pass. The Victorian Baptist preacher, C.H. Spurgeon, said this:

I believe that every particle of dust that dances in the sunbeam does not move an atom more or less than God wishes – that every particle of spray that dashes against the steamboat has its orbit, as well as the sun in the heavens – that the chaff from the hand of the winnower is steered as the stars in their courses. The creeping of an aphid over the rosebud is as much fixed as the march of the devastating pestilence – the fall of . . . leaves from a poplar is as fully ordained as the tumbling of an avalanche.

This is entirely in line with Jesus’ own comments in Matthew 10:

Aren’t two sparrows sold for a penny? Yet not one of them falls to the ground without your Father’s consent. ³⁰ But even the hairs of your head have all been counted. 

Jesus is saying God controls all things. He is sovereign over all things. There is nothing over which he isn’t sovereign. Both Jesus, and Spurgeon after him, are thinking of the smallest things they can point out and making the point that God remain in control of it. R.C. Sproul points out here why even ‘one maverick molecule’ causes us a problem when it comes to any of God’s plans:

What has that got to do with our free will? Well, if our will is entirely free, there is something in the universe over which God has no control. And that something is considerably bigger and much more significant actor than one maverick molecule. But the problem expands even further because, it’s not not only our will that is then free, but the will of every human who has ever lived. There are, then, billions of things operating outside of God’s sovereign control, having significant daily impact in the world, and God can do nothing about them.

But if even one maverick molecule can derail God’s plans, how much more will the complete free will of the multitudes of people who have ever lived? If God cannot compel our will, God has no control and cannot fulfil any of his plans.

The problem of blasphemy

Perhaps the biggest problems with asserting our free will over God’s ability to chose whom he will save is that it blasphemously puts us and our authority above God. Here is R.C. Sproul explaining how that occurs:

If God is not in control of the human will, if he is not sovereign over that, we are saying that we are sovereign. Not only are we sovereign, but God is impotent. We are in control and there’s nothing God can do about it. There’s nothing he can do to change it. This is nothing short of blasphemous.