All of the promises of God are complete in Jesus. They are final. They are achieved ultimately in Jesus’ death, burial and resurrection. The chief promise is in regards to our salvation.
John Calvin said in his commentary on 2 Corinthians that these promises are “testimonies of Divine grace.”
…although God shows kindness even to the unworthy, (Luke 6:35,) yet when promises are given in addition to his acts of kindness, there is a special reason — that in them he declares himself to be a Father. Secondly, we are not qualified for enjoying the promises of God, unless we have received the remission of our sins, which we obtain through Christ. Thirdly, the promise, by which God adopts us to himself as his sons, holds the first place among them all.
Amen, amen and amen!