The Ibrox men now boast a 14-point lead at the top of the third flight with a game in hand but with 19 games remaining, McCoist is taking nothing for granted.
He said: "I can't say the league is over and I never would say it and be disrespectful to the opposition.
"But what I will say is that was a big three points for us. Coming off the back of the Stranraer result, everyone was looking to see how we would react.
"We were playing the team closest to us and they were making one or two noises about the game. They felt they were unlucky in the last game at Ibrox and they are a good team.
"But I felt the better team won on the night - there's no doubt about that. It was the complete opposite from Stranraer. I was delighted from start to finish.
"There's been a lot of hostility towards our club and that was the case tonight. We used to love that and our boys looked like they loved it too."
Dunfermline boss Jim Jefferies praised his young teams' commitment.
"We contributed to some of the Rangers goals with sloppy mistakes but they are young boys and I hope they can learn from it," he said.
"But as far as commitment, as far as having a go, I thought they were tremendous.
"They worked their socks off and had some good spells of passing but you don't get away with the mistakes we made against a side like Rangers.
"The criticism that they got after the Stranraer match was always going to fire them up and they showed us respect by playing well.
"But we had a couple of great opportunities in the first 20 minutes and there are a lot of positives for us to take out of this."