Is Christianity A Religion?

On Trinity Sunday the church emphasizes that the living God is a Trinity of Father, Son, and Holy Spirit. Trinity is not a word found in Scripture, rather it is a formulation within the Christian religion drawn by the church from Scripture in concert with the Holy Spirit. It took the church three centuries to arrive at the creedal statement about the Trinity set forth in the year 325. In the Council of Nicaea we see how the Holy Spirit works with the church in the development of the Christian religion. But I also know that some modern protestants balk at Christianity being referred to as a religion. So today I want to address the question: Is Christianity a Religion?