McCullum and his side have come under intense scrutiny in recent weeks after a horrible start to The Ashes, dropping the first two Tests and putting up little resistance with the bat.
They have been bowled out for 172, 164, 334, and 241 in their four innings, with Joe Root the only batter with an average above 30 for the series so far.
The poor form of Ollie Pope and Jamie Smith, in particular, has left many scratching their heads at why Jacob Bethell has not yet been given a chance.
However, McCullum is adamant the team will stick with the players who have done the job for them over the last year and a half.
"From our point of view, we've had a top seven now for a period of time and we've been reasonably successful with it," he said.
"These conditions should suit the style of batters that we've got as well. We know we haven't got enough runs so far in this series.
"We've been in positions where we could have and made some mistakes, and that can happen at times.
"But for us to go on and win this series, it's not about throwing out what has been successful for us over the last few years. It's about having more conviction.
"It's about making sure we have our plans and our disciplines around it just screwed down a touch more; making sure when we walk out there, we have utter belief in what we are capable of achieving.
"Knee-jerk reactions and chopping and changing settled batting line-ups is not really our way."
McCullum, who signed a contract extension with the England Cricket Board last year, also says he doesn't pay much attention to speculation that his role as head coach might be in jeopardy.
"It doesn't really bother me, to be honest," he said. "I certainly don't coach to protect the job; I coach to get the best out of people, and that's the same with the skipper [Ben Stokes].
"We'll remain committed to what we're doing in the same way that we do, and we'll keep trying to build the confidence levels within the group to give ourselves the best chance.
"I firmly believe that if we play our best cricket, we have a massive chance in this Test match. If we do that, then the narrative changes and the series momentum changes."
Australia have one hand on the Ashes urn as they finished day three of the third Test with a commanding 365-run lead over England with six wickets in hand at Adelaide on Friday.
Marcus Trescothick has insisted England won't give up, despite the Ashes appearing to slip from their grasp during the third Test against Australia in Adelaide.
Nathan Lyon became Australia's second-highest Test wicket-taker after Shane Warne in day 2 of the third Ashes test in Adelaide on Thursday.
Australia ended day 2 of the third Ashes Test well on top as they reduced England to 213/8 in pursuit of 371 to set a first innings lead in Adelaide on Thursday.
