How much agency do we have in our own spiritual rebirth?
In short: A lot. Ultimately, we decide.
The power to act is sort of like the power in an electrical circuit. It comes from the Lord, and it's the power that created everything, including the power to act that all living creatures have. We're plugged into it, so we can DO things.
What determines WHAT we do with the power that we're tapped into? We have two "faculties": our will, and our understanding. They work together. They're both interesting mixtures.
You can see these two faculties in animals. Some of their will — what they want, love, and intend — is instinctive. It's baked in. And to some extent it can be shaped, or trained. The things they love can change, at least somewhat, in higher animals. Their understanding grows, too, from a base of instinctive knowledge, to a store of learned knowledge. Dogs develop a love for their people, and they learn the words for "cookie", "walk", "car", "sit", etc.
In human beings, there's a discrete jump in these faculties. We have a spiritual life intertwined with our physical life. We are tapped into the "spiritual power" circuit. We have immortal souls. We're finite, but we're made in the image and likeness of God.
The challenge is that with spiritual power comes spiritual responsibility. When we're born, we each have our own "personality," a unique mix of will and understanding — things we love, and things we understand. As newborn infants, most of those things are still quiescent, potential, undeveloped. But we love our mothers and fathers, and milk, and being warm and safe, and we understand how to nurse, and how to get attention.
Then, as we grow up, we learn many things, and our loves take shape. It doesn't take all that long to reach the "terrible twos", where doing things "my way" is a common thing.
How much agency do we have?
In New Christian teaching, our agency in regeneration — the process of spiritual rebirth and transformation — is significant... but always partnered with the Lord’s power. The Lord calls us to repentance and a new way of life, as seen in the Lord’s call to repent and believe in the gospel (Mark 1:15). The New Christian doctrines further clarify that while the power to truly regenerate is from the Lord alone, each person must actively cooperate through repentance, shunning evils as sins, and striving to live according to truth (True Christian Religion 330, Divine Providence 148-151).
The Lord provides all the means — truths, desires for good, and spiritual strength — but we have the freedom to choose whether to accept, respond, and act. We are to prepare the way, make straight the paths, and remove obstacles, but the actual cleansing, healing, and empowering for spiritual life is the Lord’s work in us (Luke 4:18-19, Arcana Coelestia 8388, 8393). This mirrors the examples when people approached the Lord for healing; their initiative was essential, but the healing itself came from Him.
Regeneration is a partnership. Our agency is exercised in freely choosing to turn to the Lord, resist evils, and live by truth, but the transformation of our inner life comes from the Lord working in us and with us, only with our willing cooperation (Divine Love and Wisdom 114, Divine Providence 99). Even the power to throw the switch — to open the door — comes from the Lord.
We make the decision, tap the power, throw the switch, and the Lord flows in. But we're fickle. A few minutes later, our selfishness gets back in charge, and we close the door. And then something moves us to a better part of our nature, and we open it again. Back and forth, over and over again. Gradually, over time, we have a long-term trend towards good or evil, and our ruling love becomes more entrenched. But even if we're tending towards evil, the power to turn our lives around is still there, available to us if we reach for it.
"Behold, I stand at the door, and knock: if any man hear my voice, and open the door, I will come in to him, and will sup with him, and he with me." Revelation 3:20.
