Deep rest comes when we know God.
We trust God when we've come to know and learned to rest, in His character. We rest in His character as described in the Bible:
"Yahweh, Yahweh, the compassionate and gracious God, slow to anger, abounding in love and faithfulness..." - Exodus 34:6
For many, this is not the God they see behind Christianity. To them, the God of Abraham, Isaac, and Jacob seems remote, capricious, unknowable. To others, he seems angry and destructive. Perhaps they feel this way because of what they once read in the Old Testament or learned from fiery preachers long on legalism and short on God's mercy and grace.
However, far from being a history of a harsh God, the Old Testament is actually a record of a God who is patient in the extreme—often taking thousands of years before he makes a move. As Hans Kung once observed: God's usual course of action is one of grace. But grace no longer amazes us. We have grown used to it; we take it for granted.
"He is indeed long-suffering, patient, and slow to anger. In fact, he is so slow to anger that when his anger does erupt we are shocked and offended by it. We forget rather quickly that God‘s patience is designed to lead us to repentance, to give us time to be redeemed. Instead of taking advantage of this patience by coming humbly to Him for forgiveness, we use this grace as an opportunity to become bolder in our sin. We delude ourselves into thinking that either God doesn’t care about it or that he is powerless to punish us." - R. C. Sproul
When God unleashes the consequences of sin, we become offended as Abraham was when God informed him of the coming destruction of Sodom and Gomorrah. We are offended because we convolute the meaning of grace, mercy, justice, and injustice.
It is impossible for anyone anywhere or any time to deserve or earn grace. The same goes for mercy. As soon as we speak of someone deserving something, we are no longer talking about grace or mercy, we are talking about justice. By definition, only justice can be deserved.
Suppose 10 people sin equally. Suppose God releases the consequences of their sin on five and is merciful to the other five. Is this injustice? No! In this situation five people get justice and five people get mercy. No one gets injustice. The Creator is not obligated to treat all creatures equally, not even mankind.
He is always just, but God is never obligated to be merciful and gracious.
We receive either of these two from God: justice or mercy. They are two sides of the same coin. We never receive injustice from his hand.
When God‘s justice falls, we are offended because we think God owes us perpetual mercy. The antidote to this perspective is to know God by spending time with God. Instead of harboring Eve's suspicion, we trust because we know this God for ourselves, we have seen His love in action for ourselves, and the Holy Spirit has enabled us to love him and receive love from him.
"And this hope will not lead to disappointment. For we know how dearly God loves us because he has given us the Holy Spirit to fill our hearts with his love." - Romans 5:5
In the formula I've been sharing, trusting comes after we know and love God:
To know Him is to love Him.
To love Him is to trust Him.
To trust Him is to obey Him.
To obey Him is to follow Him.
To follow Him is to die to our self/absolute surrender and walk in abundant life.
We are able to trust God, regardless of our circumstances, because we know him as the God who gave himself for us, abides in us, and keeps his promises, though they may take a long time to see fulfilled. How we think about God changes (revelations, experiences, loss, etc.) but God doesn't. When we trust God, we belong to the great cloud of witnesses to the faithfulness of God who refuse to reduce God to the world we see. Instead, we take the long view—the really long view as in Habakkuk 3:
"Lord, I have heard of your fame;
I stand in awe of your deeds, Lord.
Repeat them in our day,
in our time make them known;
in wrath remember mercy."
In other words, while the world marches in hedonistic lock-step toward God's wrath, we rest in His mercies: the awesome deeds of our God who sends himself to rescue and revive us with His life—individual revival, pockets of revival, and great reformations that rescue entire generations.
Do not mistake this life of God: It is holiness. It is the power that healed the sick, held him to the cross, and raised Christ from the dead. The task given to followers of Christ is to bear witness to the holiness of God—to be His image-bearers—just as Christ is:
"...for it is written: 'Be holy, because I am holy.'" - 1 Peter 1:16
It is a mistake to think holiness is attainable, but it is also a mistake to think it is not receivable. Holiness is a part of the deposit or downpayment from the Holy Spirit. It is part of the future age of the Kingdom of Heaven, breaking in to this current age. The fruit of the Spirit is the fruit of the life of God, living inside us.
Holiness is God's power—power over death and the profane. It is what we transmit when we transmit Christ's life to a dying, profane world. Holiness is Christ's life itself, not just what He did.
Once, when I was traveling for business in California, I stopped off at some isolated California beach. I was desperate to breathe in the openness of the coast since I was living in the land-locked, bug-paradise of south Georgia. As I rested in the faithful waves and rushing wind, I had the strong sense of someone sitting just behind my right shoulder. I turned but no one was near. Then I distinctly heard a man's voice, deep and conspiratorial. It said, "What is god?" (Notice, not WHO is god, because that assumes there is one. Instead, it said "what".)
I presume now, that this was some kind of deceiving spirit that roams California, drawing unsuspecting people in deceptive philosophies. Makes California make a little more sense, actually, considering all the weird philosophies embraced there. (Yes, I'm fully aware that any non-believing, non-Spirit-filled person reading this will likely think I'm the weird one here.)
From deep within me rose a clear response: God is holy. His essence is holiness. Holiness is the "ness" of God.
With a dismissive wave of my hand, I said this out loud and the presence vanished.
Knowledge without trust is like a locked back door that isn't shut all the way—until it clicks you can't rest in safety.
"With the cleansing from sin and the declaration of divine forgiveness, we enter into a peace treaty with God that is eternal. The first fruit of our justification is peace [or rest] with God. This peace is a whole new peace, a peace unblemished and transcendent. It is a peace that cannot be destroyed." - R. C. Sproul
If we know and trust God as the Faithful And True God, we find rest in knowing he will keep all his promises, including the promise to complete his work of holiness in us. Trust is resting in the faithfulness of God to his own character.
"Oh God, Thou hast made for us for Thyself, and our hearts are restless until they find their rest in Thee." - Saint Augustine