Here are the relevant verses ...
And it shall come to pass, [that] in all the land, saith the LORD, two parts therein shall be cut off [and] die; but the third shall be left therein. And I will bring the third part through the fire, and will refine them as silver is refined, and will try them as gold is tried: they shall call on my name, and I will hear them: I will say, It [is] my people: and they shall say, The LORD [is] my God.
ZECHARIAH 13:8-9
...I suspect they will have faith in Jesus Christ as the Son of God, and Messiah.
The bottom line on why Christianity is true, is that the Bible says what happens thousands of years before it happens. Please see http://www.yfiles.com/y3nf.html
Christianity doesn't stand or fall upon the veracity of the Bible. Christianity stands or falls on whether or not Jesus Christ is whom He said He was. If Jesus Christ is not the Son of God, the blemishless lamb of God who comes to wash away the sins of the world, then the greatest movement since the invention of mankind is entirely predicated on a lie. Who would knowingly and willingly die for a lie (suffering excruciating torment and torture in the process)? All but one of the apostles died violent deaths. Furthermore, and that notwithstanding, the empty tomb needs a suitable explanation.