Final answer:
Johann Sebastian Bach is considered the apex of Baroque music, known for his mastery of contrapuntal art and for being a virtuoso organist.
Step-by-step explanation:
The composer who is considered the apex of Baroque music and dedicated all of his works to God, was renowned for his mastery of contrapuntal art, was a virtuoso organist, and absorbed influences from international styles is Johann Sebastian Bach. Bach's contributions to Baroque music were pivotal, and his works continue to be celebrated for their complexity, depth, and technical brilliance. As a deeply religious person, Bach often inscribed 'Soli Deo Gloria' (Glory to God alone) on his compositions, indicating his dedication to his faith through music.