The roots that feed the Waldo County-based folk-rock group Tree By Leaf are wrapped around solid rock.

And that’s a good thing, said principal songwriter Garrett Soucy.

A careful listen to the trio’s new CD, “There is a Vine,” reveals Soucy returning to his Christian faith as a theme in his lyrically sophisticated songs. Soucy mostly celebrates his faith rather than preaches it, and in at least one tune, consciously delineates himself from the Religious Right.

Tree By Leaf – Soucy on guitar and lead vocals, his wife Siiri Soucy on lead and backing vocals, and Cliff Young on piano and organ – perform tonight at the Rockport Opera House in a CD release event. Joining them on some songs will be a bass player, electric guitar player, drummer and flute player, reflecting the richer tapestry Tree By Leaf began to weave on 2005’s fine record, “Of the Black and the Blue,” and which continues on “There is a Vine.”

“When we first started making music,” Garrett Soucy, 28, said, “we were young and we were [living] in the Bible Belt, and we were steeped in our faith.”

Some songs on “Evening Treatises” (2000), “Works of Mercy” (2001) and “Postcard from Rome” (2003) could be seen as reflecting Soucy’s Christian faith, though often metaphorically or with images that one would have to analyze with a Christian frame of reference to see any connection to the faith.

In the last three or four years, Soucy said he veered away from that faith, but has since experienced “a reformation within myself.” At the same time, he rejects any attempt to label this latest collection “Christian music.”

“You can’t make ‘Christian music.’ Only people can be Christian,” he said.

On “His Banner Over Us Is Love,” Soucy sings: “I’m not a patriot. I don’t pledge the flag or worship it. And there’s only room in this body for one King and it’s not democracy. Don’t bow down.”

The contagious chorus of “Don’t bow down” exhorts the listener to avoid what Soucy describes as a kind of political idolatry.

“Nationalism is the main idol in our country,” expressed by war and mass consumerism, he said.

Then there is the celebratory tone of “God Is Good,” the intimate communion in “You Have Always Met Me,” and the playful dialogue with God in “Over and Under.”

The CD also features plenty of grown-up songs about love and relationships, with the kind of stick-in-your-ear wordplay that has become Soucy’s trademark. There’s even some unabashed pop sounds on this record, like the irresistible melody that Siiri nails on Garrett’s song “Believe It.”

In developing the songs, Garrett said the group learned to “not be afraid of pop melodies if they’re there.”

Young, whose melodic piano runs are also a signature sound for Tree By Leaf, said he likes the musical variety of “There is a Vine.”

“I think this record is a little more varied,” he said, both thematically and sonically.

Siiri Soucy sings lead on more songs this time out, Young noted, which also lends a change of pace to the recording, as does a jazzy flute which graces a couple of the tunes. And there’s no missing the more percussive nature of several tunes, achieved by the drum work of Eric Sanders and the aggressive attack Garrett Soucy uses on his acoustic guitar.

“This is the most produced record we’ve done so far,” Soucy said, yet it consciously is a long way from sounding radio-tailored.

Soucy is already writing songs for the next record, and noticing that a pop-rock sound creeping out of them.

Singer-songwriter John Francis will open for Tree By Leaf 7:30 p.m. tonight at the Rockport Opera House; tickets are available $12 in advance at Wild Rufus in Camden, Second Read in Rockland, and Mr. Paperback in Belfast, and for $15 at the door.