High Priestess Levian:
You need the appropriate level and token to become a Cleric. To change profession, your level must be at least 20, and to become a Cleric, you must have the token that proves you have passed the Test of the Cleric.
You have achieved a sufficient level, but it seems you have not yet passed the test. You will be acknowledged as a true Cleric only when you have proved your faith in the Test of the Cleric. Priest Zigaunt of our temple is in charge of making that determination. He will test your faith. To change profession to become a Cleric, you must pass his test and bring back the mark of faith as proof.