cheating on Jesus

Let us remember that [God] is holy and he is righteous, and that a holy and righteous God has the right to say that the blood is acceptable in his eyes and has fully satisfied him.
-Watchman Nee (1903-1972)

I've been reading through The Naked Gospel by Andrew Farley and it has been really faith-challenging, in a good way.
One chapter was about "cheating on Jesus," something that I find myself struggling with.

In the Old Testament, we see that the Israelites have to offer animal sacrifices over and over because no single sacrifice was enough to cleanse them of their sins. Everytime they sinned, they had to offer another animal blood sacrifice.

[The law] can never, by the same sacrifices repeated endlessly year after year, make perfect those who draw near to worship. Otherwise, would they not have stopped being offered? For the worshipers would have been cleansed once for all, and would no longer have felt guilty for their sins.
-Hebrews 10:1-2

The Old Testiment makes the statement of a sacrifice that is enough to cover our sins once and for all, initiating the New Covenant. When John the Baptist sees Jesus, he declares, "Look, the Lamb of God, who takes away the sin of the world!" (John 1:29).

Because Jesus' sacrifice cleansed us once for all, there's no procedure we have to do to remain forgiven. We depend on this one sacrifice for a lifelong forgiveness. "Christ died for sins once for all, the righteous and the unrighteous, to bring you to God" (1 Peter 3:18).

"Without the shedding of blood there is no forgiveness" (Hebrew 9:22). No amount of dialoguing with God about our sins will bring us more forgiveness. No amount of asking God to forgive us will initiate his cleansing in our lives. Blood sacrifice is the only action that results in forgiveness and cleansing. This was true in the Old Testament, and it is still true today.

Because there are no more blood sacrifices being made for sins, can we not conclude that Jesus Christ's sacrifice is sufficient to bring a lifetime of forgiveness?

Here is where I find struggle.
Our human pride won't allow us to enjoy this kind of grace. Maybe it's because it feels too easy, not having to do anything.
We feel like we need to activate this forgiveness by doing some sort of procedure, asking God for it. When I became a Christian, I asked God to forgive my sins. But after reading this chapter in this book, I'm realizing that I was already forgiven. The cross is a historical event. We cannot initiate forgiveness; only blood brings forgiveness.

Farley puts it this way:
"Our acts of remembrance, confession, asking forgiveness, and claiming - whether done with good intentions or not - don't cause more blood to be shed...
Realistically, we only have two choices: (1) accept as fact the complete unconditional forgiveness that God purchased through the crushing of his Son, or (2) create some system of our own to feel better about our sins.

What then are we saying about the sacrifice of Jesus when we insist that something further be done to "activate" it? In essence, we're insulting the work of Calvary. We're valuing the Son's sacrifice even less than the people of the Old valued their animal sacrifices."

I can definitely see what Farley is saying here, and I'm starting to understand the difference between forgiveness and mercy. We don't have to do anything to be forgiven, because the cross already took care of that. However, once we accept this forgiveness, we receive God's mercy, which will bring us closer to Him and fills us with passion and desire to know God more and share this love with others.