The Jewish authorities challenged Jesus' authority to be teaching in the Temple because he was not credentialed by them. It is our faith and the Gospel itself that gives us the authority to go out and do great things in the world, not any other title or credential we hold.
Based on Mark 11:27-33:
As Jesus was walking in the temple, the chief priests, the scribes, and the elders came to him and said, ‘By what authority are you doing these things? Who gave you this authority to do them?’ Jesus said to them, ‘I will ask you one question; answer me, and I will tell you by what authority I do these things. Did the baptism of John come from heaven, or was it of human origin? Answer me.’ They argued with one another, ‘If we say, “From heaven”, he will say, “Why then did you not believe him?” But shall we say, “Of human origin”?’—they were afraid of the crowd, for all regarded John as truly a prophet. So they answered Jesus, ‘We do not know.’ And Jesus said to them, ‘Neither will I tell you by what authority I am doing these things.’
(New Revised Standard Version Bible: Anglicized Edition, copyright © 1989, 1995 National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved worldwide. http://nrsvbibles.org)