One of the most frustrating evenings in theater is The Mess. One moment, you’re moved by ineffable loveliness, the next you’re groaning at ham-handed ineptitude. Such is the careening quality of the new biographical musical Soul Doctor, subtitled The Journey of A Rock Star Rabbi.

The production, currently at the Colony Theatre on Miami Beach and moving later to the Parker Playhouse in Fort Lauderdale, shuttles between the kind of infectious entertainment that has the audiences clapping with the music and later wanting to throw vegetables at the stage.

The soul doctor of the title is not Ray Charles, but Shlomo Carlebach, the rabbi legendary among many 20th century Jews for transforming Jewish music in America from stolid dirges to uplifting paeans focusing on the joy of religion.

The musical hops, skips and often trips over the bullet points in Carlebach’s life: a Holocaust refugee who rejected some strictures of Orthodox Judaism to emphasize a humanistic, loving ethos. Along the way, the composer built an evangelistic career reclaiming disenchanted Jewish youths and performing his songs in coffee houses and rock festivals from San Francisco to Moscow to Jerusalem.

That is, in fact, Soul Doctor’s primary asset: Carlebach’s melodies soar and swell like human emotions transmuted into musical notes. Steve Margoshes and Seth Farber deftly created a lush score from 30 of Carlebach’s songs. The music has been married to a few of the rabbi’s lyrics, but mostly the words are ones that David Schechter wrote for this production.

What sinks this show is lead-footed scene after scene written by director Daniel S. Wise. Time and again, Wise gives us one-dimensional characters playing out clichéd situations with hackneyed pronouncements. The scene of Timothy Leary dangling hits of acid to tempt Carlebach’s flock of cartoonish hippie converts is particularly but representatively painful.

Just as destructive are Schechter’s lyrics that veer from occasionally evocative to frequently banal. One lyric has a lost soul appeal to Carlebach: “Doc, can you help me score some ‘ludes / So I don’t have to resort to glue.”

But every time you’re ready to give up on the show, a Carlebach melody snares your spirit or a performance resonates with your core. For instance, Merideth Kaye Clark plays that lost soul who attaches herself to Carlebach only to lose him to another woman. Clark wraps her vibrant mezzo-soprano around the heartfelt lament, I Was A Sparrow, which contains Schechter’s best lyric.

But most notable is Erica Ash who kicks the show up several notches every time she strolls onto the stage as Carlebach’s friend, the famed chanteuse Nina Simone. Her appearance 45 minutes into the show, crooning a sinuous I Put a Spell On You just underscores the mediocrity of all that came before.

Another asset is actor Eric Anderson in the title role. With a quiet magnetism, gentle smile and shining eyes, you can see the pure joy of the music transfix Anderson’s face every time he sings.

The most disappointing performance came from Gary Morris, a veteran country singer who won plaudits for his Jean Valjean on Broadway. Morris’ double roles as the elderly Shlomo and his father were so tamped down, so dulled that you wanted to feed him a five-hour energy drink.

The creators bill this as a pre-Broadway tour. But while an older Jewish audience will gladly forgive this show its multitude of sins, this is no Fiddler on the Roof that speaks to many cultures; this show’s future is, at best, off-off-Broadway and a lot of JCC auditoriums.