This was a great old rock band that wrote several big hits, my favorite being Miracles Out of Nowhere. I just read that John Elefante, who produced for Petra, sang with them after Steve Walsh left the band. I always liked the album Leftoverture. Petra and Kansas are related stylistically. Kerry Livgren is a strong Christian and Petra's music was definitely Christian rock. If you have never heard of Petra look into them as they were a great band in the 80s with a progressive rock sound. I'm not that familiar with Boston's music but I'd say in some ways it resembles that, but closer sounding to Kansas but with a harder rock sound.