Duron Harmon never lost faith.

Even with his team trailing, 21-3, at halftime of Super Bowl LI last month, the safety believed it was the Patriots’ day.

He told everyone who would listen — and by most accounts, that was darn near everyone in the locker room — that they were about to author a historic comeback.

Harmon proved prophetic, and his faith was rewarded as the Patriots pulled off a win for the ages, dispatching the Falcons, 34-28.

“It wasn’t really a pep talk,’’ Harmon said Friday. “It was really me just talking out loud about how I felt about this team. It was me just basically saying that I knew we were a great team and I knew we were capable of doing great things.

“And I really believed that we were going to make the greatest comeback in Super Bowl history, and you could feel it. People believed it. Everybody was giving positive energy and it started going throughout the team.’’

Harmon has a chance to be part of more memorable moments in New England after re-signing with the team that drafted him in the third round in 2013. The 6-foot-1-inch, 205-pound Harmon, who has missed just one game in four seasons, inked a four-year pact worth up to $20 million.

Though Harmon wasn’t on the market long, he enjoyed going through the free agent process and finding where teams valued him. He said he couldn’t be happier with the end result.

“Coming back to New England was exactly what I wanted to do,’’ he said. “I love being here. I have built a lot of relationships here outside of football. My kids go to school here.

“Being a part of this organization means a lot to me. I love playing for this organization, I love playing for Coach [Bill] Belichick, I love being a part of Mr. [Robert] Kraft’s team, and in the end, coming back here wasn’t really a hard decision. It was something that I ultimately wanted to do.’’

The deal underscores just how valuable the Patriots consider Harmon. With him in the fold, the team gets to keep its three-safety package — an important part of the defense — intact.

Though he rarely starts, Harmon played nearly 50 percent of the defensive snaps last season as teams continue to use sub packages more and more.

Patrick Chung plays more of a strong safety/linebacker hybrid role while Devin McCourty is the free safety in the base defense. When Harmon enters, generally in the center-field role to prevent offenses from blowing off the top of a defense, it allows McCourty to show off his versatility and play closer to the box.

All three safeties are considered excellent tacklers.

“It’s enjoyable playing here,’’ said Harmon. “It’s one of the reasons I wanted to come back. They know how to use me and really get the best out of me.’’

Harmon has excellent instincts and has collected seven interceptions in four seasons. He’s also a valuable special teamer.

Though the safety trio is set, the secondary will have new faces with Stephon Gilmore an addition, Logan Ryan a subtraction, and Malcolm Butler in limbo.

Harmon said it will be tough not having Ryan around, as the two have been together for eight years (college included), and he’d “love’’ to have Butler stick around but he knows each person has to do what they think is best.

“The turnover in the secondary is something we’re kind of used to,’’ he said. “How good we’ll be will not be determined now. Nothing really matters right now. All we can do is wait to get to work.

“We have to build what we’re going to be this year. Last year is last year. There’s new faces in the secondary and there’s people that might be there and might not be there but ultimately we know what we have to do to try to be a good secondary, a good defense.’’

Harmon said one area in which he is looking to improve is against the run, and he will add some weight this season to that end.

“Just continuing to build and to try and be a more complete player,’’ he said. “I would say the run area is a key [area] where I feel I can grow in.

“My tackling could be a little bit more aggressive, and I think that’s going to come with putting on a little bit more weight, being able to bang down there.’’

Jim McBride can be reached at james.mcbride@globe.com