Thomas Tuchel's side conceded first but grew into the contest, eventually finding an equaliser before completing the turnaround.
Speaking to BBC Radio 5 Live, Tuchel said there was no time for his players to doubt themselves during the comeback.
"It's easy to say now but I think there was no time for doubt. It was too intense to doubt," Tuchel said.
"This team didn't accept defeat and that's the best of it. I felt no doubt from the players. I felt that they were doing what was needed to do. I felt they showed their teeth. I felt they were fully committed again."
Tuchel admitted his side had struggled in the opening exchanges after falling behind early in the match.
"It was difficult because we conceded first and we didn't get the press right in the first 20 minutes," Tuchel said.
"Commitment was always there but in the last three quarters I think we were excellent. I felt the belief from the players, that's the best sign of it, and we created a lot of chances.
"Maybe a penalty, maybe not, and another save and another save. They kept undoing what we were doing.
"I feel like with the goal that we got, the equaliser, we got the momentum totally on our side and even more belief than we had, and turned it around. Well done."
Tuchel compared the tie to a difficult away match in the FA Cup and urged his players to keep believing regardless of the situation.
"I felt at times very aware of where we are at the moment. It's a moment in the tournament, if you want to compare it, it's probably January/February when you go to an away match in the FA Cup and things can get complicated," Tuchel said.
"It's important you keep your belief, show your teeth and don't give in no matter what. I think that's what the team deserves praise for because we did exactly this and turned it around. Well deserved by the way but it took a long while."
DR Congo defender Axel Tuanzebe said his side would need to learn from the manner of their exit, speaking to BBC Radio 5 Live.
"Ultimately we're kicking ourselves more so because we felt we should've definitely held out the game," Tuanzebe said.
"Probably should've finished it in the first half as well but it was unfortunate, it was not meant to be for us today, but we'll look on this and think how we can build for future tournaments.
"I think we'll definitely learn from this and continue attacking the game, especially early on, because having to defend wave of attack after attack against this calibre of players they will prevail and they did so today."
England captain Harry Kane, who scored during the comeback, said the team had spoken about players stepping up to have "hero moments".
"It feels amazing to be honest. What a crazy game," Kane told BBC Sport.
"They are a tough team and then after that first break we were much better and their keeper made some unbelievable saves. We spoke about people having hero moments and it can be anyone. It was me today.
"We spoke all week about just being ourselves. There are still things to work on for sure and these rounds are just about getting through. We are in the part of the tournament when you have to grind wins out, and that's what we have done today.
"We are the same as every other nation. We are through, so enjoy it. I want them to enjoy it with the fans, and then we go again in four days.
"We spoke after the Croatian game about subs making an impact and you saw that again. Over 90 minutes, we are tough to handle. I am pleased for everyone involved and hopefully we'll keep it going."