What did God do for us when we had nothing to offer?
When we had nothing we could do and could not even offer fig leaves, God showed mercy. Mercy was poured out, and He came in and did everything that needed to be done. He acted on our behalf, requiring only that we simply believe it.
Les teaches that we had nothing we could do; we didn't even have fig leaves, so we just had to stand at His mercy. But mercy was poured out: He came in and did everything that needs to be done if we'll simply believe it. In the surrounding context, this is tied to the living sacrifice of Hebrews 13:15—presenting your body as a living sacrifice from morning until night. Les says this is all God is looking for, and He asks for it rather than demanding or commanding it.