confirm, confirmation

Definition

The terms "confirm" and "confirmation" refer to stating or verifying that something is true or sure or trustworthy.

In the Old Testament, God tells his people that he will "confirm" his covenant with them. He will show that he can be trusted to keep the promises he made in that covenant.
To confirm someone as king means to agree with and support that person as king.
To confirm what someone wrote means to say that what was written is true.
The "confirmation" of the gospel means teaching people about the good news of Jesus in such a way that it shows that it is true.
To give an oath "as confirmation" means to solemnly state or swear that something is true or trustworthy.