But if one of you suffers for being a Christian, let him not be ashamed; but let him glorify God in this matter.
This very verse is the place in the New Testament where the apostle Peter, in a sense, used "the keys of the kingdom of heaven," being the first of the apostles, and even the only one, to bind the name "Christian" upon the Lord's followers as their official, holy name.  See introduction for further discussion of the "keys of the kingdom."