Mark Dever on Substitutionary Atonement & A Clarification

Mark Dever has contributed a wonderful article to Christianity Today on the issue of Christ's Substitutionary Atonement.

I asked Mark what he intended to communicate by his last line in the article, which reads:

Like Chad, we would do well to accept our guilt and admire God's grace, to let the Holy Spirit encourage us by the Savior's self-denying love to follow his example, and to savor God's love to us in this almost incredible sacrifice.

My question to Mark was:

What did you mean by "almost incredible sacrifice"? Your statement can be taken two ways - 1) Not quite incredible enough to be incredible, or - 2) Very incredible, but believable.

This is Mark's helpful clarification:

Dear Jordan,
The CT article as printed is correct. I was using “incredible” not as “very good” but as “unable to be believed” (as in, ‘this is SO GOOD it is ALMOST beyond being able to be believed’, like when we say something is “too good to be true”). Does that help?
Hope you’re well. It was great meeting you.
Your brother,
Mark D.