McGuire's first conducting position was at a church at the age of 15. She has participated as a church musician in multiple Christian denominations throughout her life, singing in choirs and playing instruments and often serving as a music director/minister. She has a deep knowledge of and appreciation for the vast canon of religious music spanning hundreds of years in Western culture and other traditions, through to America's contemporary gospel music rooted in Africa. She served as the Music Director at St Aidan's Episcopal Church in Boulder, Colorado (1996 - 2000) and Minister of Music at the Congregational Church of San Mateo in California (2011 - 2013). In 2014 she was the inaugural conductor of the Hallelujah Gospel Choir, which debuted at the Melbourne International Singers Festival.