Well, technically the religious unity never ended. I am not religious, but religion has been and will be apart of our society for as long as we can imagine.
Early on in Reconstruction Black people began opening schools and churches to help educate people how to read and write. This was protected not only by laws but the Federal troops stationed in the South and definitely South Carolina.
So Reconstruction gave free African Americans the chance to be educated. Though it was short lived once Reconstruction was abandoned.
a large, well-trained military
The US was being provocked by Germany, as German naval forces and submarines had destroyed several US merchant vessels.
Before determing the participation of the US in WWI, President Wilson sent two written warnings to Germany, explicitly posing that the relations between the two countries were at a very delicate situation. Wilson wished to remain neutral in the conflict, but he knew that it would not be possible if German attacks continued. This is why he chose to use these warnings as a manner of giving a last opportunity to Germany before performing a direct intervention.