We must not dwell on recent Premier League defeat at Bramall Lane, says Luiz.
David Luiz has told his Arsenal teammates not to let their dramatic defeat to Sheffield United de-rail their bid to finish in the Premier League’s top-four.
The Gunners fell to a 1-0 loss away from the Emirates on Monday night as they moved down to fifth spot in the league standings.
Nicolas Pepe's brace saved Unai Emery from further embarrassment in the Europa League on Thursday as his team fought hard to secure a 3-2 comeback over Portuguese club Vitoria SC.
However, speaking ahead of their match against Crystal Palace on Sunday afternoon, the Brazil defender insists his side must believe in their philosophy and keep improving.
"We have to be honest about what went wrong, but we also have to be calm," the centre-back told Sky Sports.
"It's only our second defeat this season. We are doing many things well. We have to keep believing in our philosophy, we have to keep believing in our team, which is the best way for us to improve.
"Football is about the end, not the beginning, so let's see how we finish at the end of the season in May."
Regarding the match against Roy Hodgson's impressive Eagles who sit in sixth spot, a point behind Arsenal, Luiz said: "If you want to achieve big goals, you have to think about winning, winning, winning.
"It'll be tough against Crystal Palace, but we want the three points. I want to win titles with Arsenal – that's why I'm here."