'Believers' in the Bible

many times on journeys, [exposed to] danger from rivers, danger from bandits, danger from my own countrymen, danger from the Gentiles, danger in the city, danger in the wilderness, danger on the sea, danger among those posing as believers;

Test yourselves to discover whether you are true believers: put your own selves under examination. Or do you not know that Jesus Christ is within you, unless you are insincere?