The Gunners lost 3-0 to Everton, who are their closest rivals for Champions League qualification, during a run of only two points in four Premier League games.
However, they have rallied to win their last three matches and leapfrog the Toffees to take a four-point lead over them into the final two games of the season.
"We have gone through a difficult period, and Goodison Park was one of them," Wenger told Sky Sports News.
"I believe that the spirit in the side is healthy, strong, determined and you can see that when the team is capable of bouncing back after a big disappointment."
Arsenal will secure a place in Europe's biggest club competition for an 18th consecutive season under Wenger's management if they beat West Bromwich Albion at the Emirates Stadium on Sunday.