Why is the motto “ in god we trust” present on national currency?

The use of IN GOD WE TRUST has not been uninterrupted. ... A law passed by the 84th Congress (P.L. 84-140) and approved by the President on July 30, 1956, the President approved a Joint Resolution of the 84th Congress, declaring IN GOD WE TRUST the national motto of the United States.

when a country suffers, for example, a drought period, the market product is affected for a low offer, in this case, potatoes; the government has to tax to the households, which have to give more money for the potatoes which they consume, that situation make them consume substitute goods even through loans, it could increase the financial market movement and the inflationary phenomena, the business has to increase salaries in order to the employees could buy a more expensive food (potatoes) and in order to inflation tha business had to buy expensive supplies in the factor market, while the rest of the world have to gain more money to consume the same amount of potatoes.