School authorities empowered to employ teachers in the public schools shall not prescribe as a condition of employment that such teachers shall or shall not belong to a specified religious denomination or political party, or shall or shall not have any specified religious belief, creed or political affiliation. If it be determined by the commissioner, in proceedings duly brought before him, that a board of education, board of trustees or trustee of a city or school district, or a committee or officer of such board, has violated this section the commissioner shall withhold the whole or a part of the public money next payable to such city or district.