The Toffees, who last season finished fifth and had set their sights of a Champions League spot this term, have slipped to 12th in the table, 11 points off the top four, following loses to Southampton last Saturday and against Stoke on Boxing Day.
Martinez???s side have only won one of their last six league games, with four of those ending in defeat, and struggled to create much going forward in what was a physical encounter with the Potters.
Everton must now hope to bounce back on Sunday against fellow strugglers Newcastle, who are currently on a losing run of three straight losses in the league.
And ahead of the trip to St James’ Park, the Spaniard said: “I don’t think in general we are lacking confidence, but I think this is a moment of the season that is pivotal for us – seeing how we can react.
“The reaction now has to be that we make sure we know what we are doing.
“We have a real understanding of how to perform and if we can keep that, the results will come.
“But football gives you these sorts of challenges, and this is the challenge of the season.
“We need to make sure we get through this period stronger than ever, and that could really give us a very strong second half of the season.”
Martinez admits Everton have not been “in a great moment” of late, but was keen to stress that against Stoke in particular “nothing that could have gone our way did go in our favour.”