Mehler graduated from Woodrow Wilson High School in 1969 and soon thereafter moved to Salt Lake City with two musician friends, Chuck Fraher and Jay Truax, to form Spirit of Creation. Later, he joined Chuck Girard and Tommy Coomes in Love Song, one of the pioneers of Contemporary Christian Music (CCM).
Mehler's solo album Bow and Arrow was a pioneering work in the Contemporary Christian Music scene. The album is currently hard to find and is out of print.
CCM magazine says,
"John Mehler's musical contributions have graced the "fine print" of more Christian albums than just about anyone I can think of. As a member of Love Song (one of ccm's foundational bands), his distinct style as a drummer was to have as dramatic an influence on the sound of many early Christian bands as Ringo Starr did on the British bands that followed in the wake of the Beatles. As a session player on countless records, John brings to the drums a unique musicality thoroughly individual yet always complementary to the sound of the artists he's accompanying."