In Galatians re: that specific theology of circumcision, yes, but it also takes in concepts of sowing to the flesh and reaping corruption, which is not just the circumcision issue, IMO. Re: the gospel spoken of there, Paul says a gospel different than what he proclaimed, so this is not limited to the circumcision issue.
The concept of wrong theology is spoken of in several places in the NT. There are commands to not be deceived and warnings about how deceivers, deception, teachings of demons, etc. will be in play. There are also such things as Paul dealing with resurrection in 1 Cor 15 and how he says our faith is worthless if there is no resurrection. I suppose we could consider thinking we're through the narrow gate and on the narrow way while really being in an empty and worthless belief.
False gospels, false theologies, doctrines of demons, deceptions, and so on. It does not look like a minor matter the way I read Scripture. I see a lot working against our coming to Christ and a lot working against our being raised from infancy to maturity and beyond in Christ. So, much against getting through the narrow gate and moving along the narrow way. After maturity, Paul is still speaking about enemies of Christ's cross in the context of those opposing a continual pursuit of the upward call of God and arriving at the resurrection.