Rubio is a lukewarm Catholic. Going to a protestant church when there’s a Catholic Church available is not permitted by the Church. A Catholic can attend a protestant faith on special occasions like a funeral or marriage but can not go to protestant service in lieu of Mass.
He is a Catholic, and as far as Catholic politicians go, a very good one, he isn’t even a democrat.
You should be pleased with him, not attacking his faith.
I wouldn’t even describe him as a lukewarm Catholic:
Personal life
Rubio married Jeanette Dousdebes, a former bank teller and Miami Dolphins cheerleader, in 1998, and together they have four children. Rubio and his family live in West Miami, Florida.
Rubio attends Christ Fellowship, a Southern Baptist Church in West Kendall, Florida, as well as Catholic services.
After leaving the Florida House of Representatives due to term limits in January 2009, Rubio started his own law firm. In February, he declared himself a candidate for U.S. Senate in the 2010 election cycle.
In an interview in 2012, Rubio said: “I’m a Roman Catholic. I’m theologically in line with the Roman Catholic Church. I believe in the authority of the church, but I also have tremendous respect for my brothers and sisters in other Christian faiths. I recognize, as the Catholic Church does, that there are excellent teachings of the Word throughout other denominations. The elements of salvation are found in these churches as well.”
Source: Wikipedia