Islam is a comprehensive religion belonging to all times and places. One of its characteristics is that it was revealed and introduced little by little, its fundamental principles to be believed in, being given priority over its commandments, and, in turn, some of its commandments over the others. Even, for several reasons, some of the obligatory commandments were not introduced at once unless adequate preparations were made for them.This article is trying to show that when an Islamic government IS established in a society, it is obliged (by the shariah) to implement the divine commandments immediately unless doing so will bring dishonor on Islam, due to lack of appropriate ground, even among the Muslims. Therefore, for some reasons, the most important of which is a contradiction between commandments, the implementation of commandments may be postponed to future date, but the Islamic government is obliged to make preparations for them to be fulfilled.It seems that non-usury banking and Islamic system of taxes, in the Islamic economic literature, follow this regulation.