Final answer:
Woodrow Wilson argued that it was a mistake for progressives to abandon the field of religious discourse in politics.
Step-by-step explanation:
The U.S. president who argued that it was a mistake for progressives to "abandon the field of religious discourse" in politics, according to your textbook, is Woodrow Wilson.
During his presidency, Wilson advocated for Progressive reforms at the state level but believed that the federal government should not interfere. He supported strong labor laws in New Jersey but believed that implementing them nationwide would go against principles of local control and create an overly "meddlesome" federal government.
In conclusion, Woodrow Wilson is the U.S. president who expressed the opinion that progressives should not abandon religious discourse in politics according to the textbook.