The hosts looked to be heading for a shock Premier League defeat at the Emirates Stadium, where new boy David Healy had fired the visitors into the lead after just 52 seconds following a Jens Lehmann mistake.
The Frenchman said: "We had a horrible start and were playing against a good Fulham side, a good goalkeeper.
"This is the kind of result that can change a season for a team. It's a positive start."
Wenger continued: "You can get momentum from these things, and especially belief.
"Nobody could ever measure it in terms of psychology, but it is important.
"To have lost the game today would have been a big blow for the team because everyone would have said it was after Thierry Henry had left."
Wenger revealed Lehmann was "the happiest boy in the dressing room", following Arsenal's recovery.
The veteran had earlier made a complete hash of an attempted return pass to the defence, striking the ball against his left leg and gifting possession to Healy, who slotted into an empty net for a first top flight goal.
Wenger said: "First of all, I was surprised he had made the mistake.
"He's an experienced keeper and you want to deal with your first ball.
"Jens changed his mind, but wasn't quick enough to respond to his brain. He lost his co-ordination."
Wenger added: "Every goalkeeper can make a mistake. He made one. If you are an outfield player you are not punished, but you are in goal."