Setting aside the quality of the finished product for a moment, I admire those involved with the making of “The Shack” for even taking on a film with such a literal and bold interpretation of the Christian faith.

Let’s put it this way: When one character says he always pictured God as a man with a white beard, the (very different) version of God we see onscreen chuckles and says, “Sounds like you’re thinking of Santa Claus.”

When William P. Young’s Christian novel “The Shack” became a mega-hit in the late 2000s and early 2010s, selling millions of copies, some critics derided the book for its interpretation of Scripture — including the physical manifestations of the Holy Trinity:

• An African-American woman as God the Father

• A Middle Eastern carpenter as His son, Jesus

• An Asian woman as the Holy Spirit.

The film adaptation stays true to those depictions, with Octavia Spencer as God the Father, aka “Papa,” aka “Elousia,” the Israeli actor Avraham Aviv Alush as a rather mischievous and hippie-like Jesus, and the beautiful Japanese actress Sumire Matsubara as the Holy Spirit, aka Sarayu.

And while the gospels of Luke and Matthew indeed say Jesus was a Jew born in Bethlehem, to say “The Shack” offers a new spin on the Holy Trinity — and some provocative theories about free will, forgiveness and the afterlife — is an understatement. No doubt some Christians will be taken aback and perhaps even offended by the storyline.

The religious debate can and should continue outside the boundaries of this review. (I welcome your feedback.) As always, the primary purpose here is to give you my opinion of the movie’s merits — and on that count, “The Shack” is a well-acted and sometimes moving but far too often slow-paced and unconvincing spiritual journey.

Sam Worthington (“Avatar”) is Mackenzie Phillips, a name that took me out of the movie for a moment because Mackenzie Phillips is the name of the actress and singer whose father was John Phillips of Mamas and Papas fame

Anyway. He’s called “Mack” most of the time, so we’ll go with Mack.

Struggling to hide his Australian accent and looking quite like a 20-years-ago Pierce Brosnan, Worthington plays an American living in the Northwest who is mired in a place of great sadness and has essentially lost his faith after the disappearance and murder of his youngest daughter, Missy (Amelie Eve).

Mack’s wife Nan (Radha Mitchell) still believes in God and is doing her best to hold the family together. Their son Josh (Gage Munroe) and their daughter Kate (Megan Charpentier) haven’t exactly turned into wild teen rebels, but Sam is so mired in his own grief, he’s disconnected from the children, especially Kate, who blames herself for Missy’s death.

One blustery day, Mack finds an unstamped envelope in the mailbox from “Papa” (the term his wife uses for God), inviting him to meet up at the shack — the very shack where Missy was murdered. With no way of knowing if the note is from the killer or a cruel prankster, or perhaps some other being, Mack sets out alone for the shack.

The shack is where we meet Papa and Jesus and Sarayu. The shack is where Mack must confront his tragic past, contemplate his future and make monumental decisions about the present.

Octavia Spencer plays God, literally, as a quietly calming, all-knowing presence. Alush’s Jesus is a warm and loving entity — but he’s a lightweight and is almost goofy in some scenes. Matsubara’s Holy Spirit does a lot of laughing, even when the moment isn’t all that funny.

At times “The Shack” goes extremely dark, especially in flashbacks involving Missy’s death. There’s a creepiness to those scenes, even when the intention is to depict closure.

Also a problem: Tim McGraw’s Willie, a kindly neighbor who lives across the street from the Phillips family, narrates Mack’s story. How does Willie know everything, even things Mack supposedly tells only his family about? Is Willie also some sort of biblical figure? It’s never explained, so it just comes across as kind of weird that Willie knows so much and is so invested in the Phillips family — far more than I ever felt invested as a viewer of the film.

★★

Summit Entertainment presents a film directed by Stuart Hazeldine and written by John Fusco, Andrew Lanham and Destin Cretton, based on the book by William Paul Young. Rated PG-13 (for thematic material including some violence). Running time: 132 minutes. Opens Friday at local theaters.