The brotherhood of believers says this with all certainty: No God, no glory.

The overarching theme during the Eagles' run to their first Super Bowl win was resilience in the face of attrition. The Eagles lost four cornerstone starters in 2017, but the players who form the team's Christian nucleus swear their faith took them to the top.

"The brotherhood is what got us through," said quarterback Carson Wentz on Thursday. He blew out his knee in Game 13, after which, he admitted, having to watch "sucked." But he was steadied by the brotherhood:

"Being able to do life together with other believers who are like-minded, who realize there's more to this life than just football."

To be perfectly clear: The brotherhood believes that the Eagles won the Super Bowl because their faith created an atmosphere of clear-minded, selfless determination.

"That's the underlying factor of why we're so successful," said linebacker Jordan Hicks, who ruptured his Achilles tendon in Game 8. "We faced so much adversity with key players going down. The one thing that stayed the same was the mind-set and love for each other on this team."

How deep is their faith?

They even prayed for Howard Eskin.

>>READ MORE: The Gospel according to Carson Wentz

That the Eagles have a lot of Christian players isn't news. The quarterbacks room, led by former offensive coordinator Frank Reich, often was part offensive think tank, part prayer sanctuary. Wentz, Hicks and several other Eagles, such as Philly Special passer Trey Burton and his target, Super Bowl LII MVP Nick Foles, have professed their faith often since Doug Pederson was hired as coach in 2016. A new book, Birds of Pray, begins at that point and offers anecdotal insights to the depth of their devotion. The cover features Wentz, Ertz, and Burton practicing their pregame prayer, the first inkling that what's inside will offer proof of their sincerity … because, come on, can we really believe that these young, millionaire NFL champions can really be so pious?

"I get that," Stefan Wisniewski said. "No matter what words you're saying — it doesn't matter if you're not living it. We have to walk the walk if we talk the talk. Being skeptical is a reasonable thing. But we're all living it. We're not perfect, but we're striving for perfection."

That's what the book reveals. Ertz talks about getting baptized on the eve of his wedding to Julie Johnston. Foles discusses how his belief guided him away from retirement in 2015. Wentz admits that, after his injury, prayer offset despair.

"No doubt. It's no wonder that people sometimes turn to the wrong things when they go through hard times. Sometimes, it sucks," Wentz said, and paused. "Sometimes, it sucks," he said again.

He continued, "Being able to turn to Jesus, knowing He has a plan, even though it might suck at the moment — just putting your trust in Him, and having guys around you, supporting you, encouraging. Resting on God's word to get you through. Without that, who knows what you'd turn to?"

Again and again the Eagles turned to each other: When brotherhood member Jordan Mathews was traded during training camp; when cornerback Ronald Darby, for whom Matthews was traded, was injured in Game 1; when brotherhood member Chris Maragos, a special teams captain, blew out his knee in Game 6; when Hicks and Pro Bowl tackles Jason Peters were lost in Game 7; when Wentz went down; and while Foles dealt with being a backup, then struggled as he tried to find his stride as Wentz's replacement.

"My faith in Christ was everything throughout the process. Stepping into a backup role is not always easy when you've always been a starter," said Foles, who was a backup in Kansas City in 2016, too. "Putting my ego aside. Being humble. I was never worried about success on the field. I was just worried about being a great teammate and impacting guys in the locker room in my role."

Of course, not every Eagle wears Jesus on his sleeve. That's not the point, said Wisniewski. The brotherhood, he said, set a tone of inclusion and support for a roster replete with reclamation projects, such as sensitive running backs LeGarrette Blount and Jay Ajayi, and injury-plagued receivers Alshon Jeffery and brotherhood member Torrey Smith.

"If the Christian guys on the team are lovin' everybody, encouraging everybody, having great attitudes, those kinds of things helped build an atmosphere that you want to have on a football team," Wisniewski said.

Now, for two relevant disclaimers. First, the book's author, Rob Maaddi, is a longtime friend and colleague who covers sports in Philadelphia for the Associated Press, so this is not a review, since the conflict is obvious. Second, as the son of a Baptist minister, I have no patience for fake Christians, and I've seen a lot of them. I approach every celebrity Christian with a skeptic's eye.

These Birds have passed every test, and continue to do so.

The greatest source of drama this season will be how Wentz and Foles coexist as Wentz resumes his starting role in the wake of Foles' finest hour. Foles is ready.

"Pride's right around the corner. Pride comes right before the fall. I'm aware of all that," Foles said. "I'll have my struggles. I'm aware of all that."

The book also provides excellent detail about how Jeffrey Lurie and Howie Roseman built the team, and how it won, and what key players were thinking in the biggest moments, which is cool. It details how members, even after the Super Bowl win, members of the brotherhood have participated in local outreach efforts.

Certainly, parts of the book are saccharine enough to make your teeth hurt, but that's to be expected. It isn't a mob novel. It's 142 pages of religious testimony and hometown celebration. The book might change your outlook on life. It might not.

It will, at the very least, give you a better understanding to what made this Eagles team unique, and what makes it unique still.