Appointments and promotions in the administrative service of the City shall be made according to merit and fitness; and no person in the employ of the City or seeking employment with the City shall be appointed, promoted, reduced, removed or in any way favored or discriminated against because of his race or his religious opinion or affiliations; provided, however, that Council may, by appropriate resolution or ordinance, require all employees of the City to take the oath prescribed in Section 4.102 of this article.