The Spaniard, who has replaced Aaron Ramsdale between the posts after joining on loan from Brentford, was culpable as Luton scored twice in eight minutes to take the lead.
He was caught out of position by a 49th minute corner which allowed Elijah Adebayo to make it 2-2 and then dived over a Ross Barkley shot that put the hosts in front.
Thankfully for him Kai Havertz equalised and then Declan Rice scored the winner in the seventh minute of added time to send Arsenal five points clear.
"We have to defend better the situations as a team. There are certain things leading to the goals and it's not about blaming, we have never done it, and we're not going to do it now," Arteta told reporters when asked about Raya's display.
"It's about how the team reacts to that, because it's going to happen, and I love that response."
Arteta was far keener to talk about the spirit of his side who refused to accept dropped points at Kenilworth Road - a ground Arsenal had not won at since 1984.
"We don't want a draw, we want to win! That drive, that energy, that risk and emotion that we put in the pitch, you can sense it," Arteta said.
"Today we conceded some goals that we are going to be disappointed with but that's part of it as well. It's going to happen and how we react to that, and it was great."
The only blemish on a great night for Arsenal was news that Takehiro Tomiyasu, who was unable to play, faces a lay-off.
"We had a scan, and it's not good news. He's got an injury in his calf, and he's going to be out for a while," Arteta said.
