Bach was a devout Lutheran, and his faith informed his music. Many of his pieces are based on Bible stories or texts, including the St. Matthew Passion, the St. John Passion, and the Christmas Oratorio.
Other composers
Bach was also influenced by other composers, including his own relatives (most notably his uncle Johann Christoph Bach and his father's cousin Johann Jakob Bach). He studied the music of many other composers, including Palestrina, Tallis, Byrd, Frescobaldi, Buxtehude, and Vivaldi.
The natural world
Bach was also inspired by the natural world. Many of his works contain movements that evoke the sounds of birds, animals, and other natural phenomena. For example, the "Sinfonia" from his Cantata No. 215 depicts a storm, while the "Air" from his Orchestral Suite No. 3 imitates the song of a nightingale.
Personal experiences
Bach's personal experiences also influenced his music. For example, the death of his first wife, Maria Barbara, is thought to have inspired the "Crucifixus" from his Mass in B Minor.
A desire to create beauty
Above all else, Bach was inspired by a desire to create beautiful music. He believed that music was a gift from God, and he was determined to use his talents to create music that would glorify God and uplift the human spirit.