Authorities say a teenager planned to attack churches in a northern Idaho city using a metal pipe, butane fuel, a machete and potentially his father’s guns. Eighteen-year-old Alexander Scott Mercurio has been charged with attempting to provide material support to the Islamic State group. He was arrested Saturday, and the charges were unsealed Monday in federal court. Investigators say Mercurio adopted the Islamic faith against his Christian parents’ wishes and was in contact with FBI informants posing as Islamic State group supporters. Court documents did not show if Mercurio had an attorney and phone messages for a relative were not immediately returned Tuesday.