How does the would-be Christian come to have the capacity to trust in God in Christ for salvation? In other words, do people have an inherent innate autonomous capacity to seek and believe God? Or, is it required that something or someone external to the would-be believing human agent gives them a capacity to believe? Historically, the so-called Pelagian position maintains that human beings are born in a neutral status, with a natural capacity inherent to their being to freely choose for God, or for self. Obversely, the Christian position has maintained that the human being inhabits a status that is locked into, incurved upon itself, thus requiring that God in-breaks into humanity’s heart, and gives it a new human freedom to be for God and not against Him.
There are a variety of ways various theological positions have attempted to cut this salami. For my money the only way to go is by emphasizing God’s action become human action for us. In other words, what is required for us to be for God is that God first be for us in His saving and believing action for us in Jesus Christ. What is necessary, in my view, is that human beings come to have the capacity to truly be human once again; that is, according to their purposed telos: i.e., to be in right relationship with the triune God who created them for a koinonial (fellowshipping) relationship with and in His free life of Self-given love as Father, Son, and Holy Spirit. But again, what is required for this reconciliation between God and humanity to obtain?
God freely chooses to create humanity in His image; the imago Christi (see Col. 1.15). Humanity in Adam and Eve inscrutably choose to doubt God’s Word for their own serpentine inspired word. As a result, humanity is plunged into death and trespasses, into a ruptured relationship with the living God. In this rupture humanity’s purpose for being human is lost into a strange wanderlust of sub-humanness. In this new and dead status all humankind can do is to seek themselves, driven by the “purpose” of their own self-possessed base desires. The freedom they once had for God has become sublimated by a “no-freedom” wherein the only choices available to them is to ultimately be for them; driven by sorted and competing self-affections that leads to the passing pleasures of sin.
This has become humanity’s status in the first Adam. But because of who God is, He is free graciousness, He is Self-given love within His interpenetrative subject-in-being life as Father, Son, and Holy Spirit, and because of this “who-ness,” the very who-ness that freely chose to create human beings in His image to begin with, He chose, from the very beginning, to not be God without us, but with us. That entailed that He had already freely and sacrificially bound His being to ours, to human being; not as its predicate, but as the predicator of human life in and through participation, by fellowship with Him. As such, if this status of relationship with Him, which is the very purpose of what it means to be human, was to be maintained, particularly in light of the Fall (but not because of it), God, in keeping with who He is, because ‘He cannot deny Himself,’ became the Logos ensarkos (the Word enfleshed). He who knew no sin became sin for us that we might become the righteousness of God in Him. In this becoming He assumed our subhumanity, our sinful statuses for Himself, and by this poverty made us rich by His riches of resurrection and ascension. It was by, and it is by this Divine action that humanity comes to have the capacity they were always already created for: to be free for God, and for Him alone. As Christ became us, by grace and adoption, by His recreation for us, we became recreated in Him; indeed, He who is the second and greater Adam. In this action He has exalted humanity in His elect status as the Son of Man, as the Word of God, as the man from Nazareth, Jesus Christ.
All of the above to say: that outwith this “intervention” of cosmic undertaking, left to ourselves we would remain in the bondage of the self, incurved upon the vein satisfaction of our darkened hearts, with only destruction and non-being as the “purpose” for our existences. Left to ourselves we wouldn’t have the capacity, the resurrection power, the grace of recreation to be for God. As such, what has been, and is required, is that God give us a heart of flesh that is soft for Him, rather than the hearts of stone we are born enslaved to. Without God’s humanity humanity could not and would not ever be; not to begin with, and not in the great forthwith. But because God has covenanted with us in the Son, because He has first unilaterally acted for us in a way that we wouldn’t act left to our self-slaved hearts, we have come to have the freedom for God that God has for Himself as we share in that through the vicarious humanity of Jesus Christ. God calls, and we respond. He has made a new way for that, new relative to the old of our dead-man statuses, by forging a new humanity, an elevated humanity, in the resurrected and ascended humanity of Jesus Christ. He graciously placed us into Himself, as He assumed our humanity as His in the humanity of His dearly beloved Son, as that pierced through the womb of Mary in that still silent night in Bethlehem. As a result, humanity, by the power and awakening work of the Holy Spirit, has come to have the capacity to genuinely and freely be for God and not against Him. But this only as a share, as a participatio in His original, eternal freedom as He is unboundedly Father, Son, and Holy Spirit.
What should be immediately apparent, and with this we close, there is only One freedom to have, to be. God’s freedom is the only freedom available. There is no independent human agency, no autonomous human freedom, no non-contingent life or reality, outwith God’s upholding Logos. So, the “trick” is to come to an understanding whereby humanity can be participant with said freedom. And the answer is God’s choice to not be God without, but with us, Immanuel. He has brought His freedom to us, He has grounded that for us as the anchor of our souls, in the humanity of Jesus Christ. And by this unio mystica (mystical union) between God and humanity and humanity and God in the hypostatic union of the eternal Son with conditional humanity, it is in this union, all of it an ontological reality from the very first creation, that our hearts of stone are removed and we are given to participate with the Son’s human heart for us. It is by this that we might say Yes and Amen to God because God first is the Yes and Amen for us in the face of His Son for us, Jesus Christ.

Emet… Hallelujah! Thanks be to God!
@Richard, amen.