As a result, Leeds replaced the Toffees in the drop zone and are a point from safety.
The Elland Road outfit had Luke Ayling sent off for a reckless challenge on Arsenal forward Gabriel Martinelli. The defender will now miss the final three games of the season because of suspension.
Meanwhile, Illan Meslier made a huge error to gift Gunners striker Eddie Nketiah the opening goal.
However, Marsch insists that unity is needed if Leeds are to stay up.
What’s been said
The Whites boss said: “If we started playing the blame games with players, we’re screwed. We’ve got to stick together and fight for points, it’s not a time to point the finger.
“The ironic thing was this was 500 games for Luke, but it was a moment of poor judgement. But he has been an incredible part of the team since I have been here.
"Young goalkeepers can make mistakes, but the rest of his game was quite good today. We are going to need him in the last three games. We have to stay positive, stay strong and forage on. The focus is fully on Chelsea to prepare for a key game.
“We dug ourselves a massive hole and made a difficult task much, much more difficult. But our resolve and fight when the game was incredibly hard was amazing.
“Our backs are against the wall. We are in the relegation zone but we have to fight for our lives. When I came here two months ago, I knew this was not going to be easy.
“The group has stayed strong. Our second-half performance highlights the character of the people we have here.
"The fans and the support at this club is unreal. We want to put a performance on the pitch that honours that support.”