In the management of the secular affairs of the church so incorporated and of the business of said corporation, but subject always to its direction and control, the board of trustees thereof shall have and exercise all such powers of the board of directors of a business corporation as are appropriate to the purposes and business of a religious corporation: Provided, however, That said board of trustees shall not choose, call, settle or dismiss a pastor or fix his salary or buy, sell, convey or incumber real estate or any right thereto or interest therein, unless instructed so to do by said corporation at a regularly called meeting: And provided further, That members of the board of trustees and such other officers as may be provided for in the articles of association shall be elected by ballot at a regularly called meeting of those entitled to vote under the articles of association.