A friendly man with a mustache, wire-rim glasses, and a deep tan from hours on the practice field, Arenz no longer coaches. He's now the Saints' athletic director, a job that includes responsibilities such as raising money for the new field and filling water jugs.
His wife wraps ankles and knees, is working on becoming a trainer, and generally serves as a jack of all trades. She was in charge of putting together the team's first-ever program for Saturday's game.
Arenz, who lives in Bel Air, spends 20 to 30 hours a week on the Saints, as does his wife. An engineer in Havre de Grace, he works from 6 a.m. to 2:30 p.m., and then goes to practice from 4 p.m. to 6 p.m.
Football coach Tony Dipaolo works a similar schedule. No one involved - not the seven coaches or the trainer - gets paid.
They see the Saints as a kind of ministry. During every practice, there's a break for a short sermon. After every game, Saints players pray, and then hand out Bibles to opposing players.
This year, the Saints will have 50 players. Most of them are home-schooled for religious reasons, and the team tends to play other Christian schools around the region. The training has become increasingly serious: This past year, during off-season, the team met three days a week at a local gym to lift weights and run.
Even so, the team is not big.
"We tend to attract a lot of wide receivers and defensive backs," Arenz says wryly. One freshman is 5-foot-3 and 100 pounds, and there are lots of kids who look like they might be better suited for running cross-country than making pancake blocks.
Arenz has had lots of help with his project.
Beachmont Christian Ministries allowed the team to use one of its fields for practice and gave the Saints permission to build a regulation field. Contractors worked for free or at a discount.
The field cost $50,000; without the price cuts, it would have been double that.
Another key contributor is Ravens kicker Matt Stover. A devout Christian, he heard about the team and through his foundation he has donated a "significant" amount of money to help the Saints. A banquet at which Stover spoke raised an additional $32,000.
"God's been very gracious to us, one way or another," Arenz says.
Arenz has high hopes for this year. "I would like to say we're going to win 10 games," he says.
It's not clear if he's actually predicting those 10 wins, or just thinking a bit wishfully. It's even possible the team may not be as good as last year's. They've lost 11 senior starters, including Arenz's son Matt, a 240-pound missile who was the team's best player. Matt is now playing in college, as a walk-on defensive end at the University of Delaware.
Even a man as optimistic as Arenz doesn't think the Saints will beat Riverdale Baptist, the Largo powerhouse that has thrashed them four years running.
"There's still a lot of room to grow," he said.