It’s not even a matter of us cooperating with God.
HE works in us to will and to do according to HIS good pleasure.
The very motivation to seek Him comes from Him Himself. We can’t even do that without His enabling.
This business of us doing it and needing the *help* of God to make it worthwhile makes it us doing it in out own strength and God is added as necessary.
One of the reasons I chose the quote from +Symeon the New Theologian was this:
“but without fire of the Spirit, everything he does will remain inactive and useless for his aim, for by itself what he does is powerless to cleanse the soul of its dirt and foulness.”
Seems clear to me that you and +Symeon are saying, at base, the same thing. Theosis is from God, not from our works. Orthodoxy teaches that absent Christ’s Incarnation, Death and glorious Resurrection, we would be doomed to a futile eternity without God in the place of the dead.