It can be described as an infringement of the principle of separation of church and state. Indeed, a secular government is not supposed to proclaim and impose days of prayer, since praying and giving thanks to God is a religious matter. However, some argue that although there is separation between church and state, there is not separation between religion and state, since the state is made up of individual persons and the Constitution guarantees freedom of expression and religious creed.
The fact that a person during his/her government work is not asked to abandon his or her religion; but only to refrain from making official decisions based on religion, or to let religion dictate the nature and the scope of those decisions, can be offered as a counterargument; but the debate keeps to rage on. With Muslims and Fundamentalist Christians trying to increase their influence in public affairs this debate will have to be resolved, soon.