Yes, there is religious freedom and religious tolerance in Nicaragua. Even inside my family we have different religions and we do respect each other.
More than 80 percent of the population of Nicaragua belongs to Christian groups. Roman Catholicism remains the dominant religion. According to the 2005 census by the government's Nicaraguan Institute of Statistics and Census, 58.5 percent of the population was Catholic and 21.6 percent was evangelical Protestant, a category that included Assemblies of God, Pentecostals, Mennonites, and Baptists.
Now, there are also some English services offered in Managua and Granada. Make sure to check on that during your visit, I'm sure you will feel comfortable.
(El Calvario Church in León, Nicaragua, pictured.)