All doctrine is important, but some doctrines are more important.
I heard a distinction used years ago (don’t know the source) that uses a three-tier distinction for doctrine. I have adapted it and found it helpful at times:
Tier-1 doctrines: Those beliefs without which one cannot be Christian (e.g., deity of Christ)
Tier-2 doctrines: Those beliefs that make it difficult for people to fellowship and worship together but that do not necessarily determine one’s standing as a Christian (e.g., baptism, tongues)
Tier-3 doctrines: Those usually labelled “non-essential” and that we should be willing to agree-to-disagree about (e.g., Bible versions, eschatology)
I acknowledge, however, that there is a problem with this in that there is often little agreement about what fits in which category.
For example, most conservative Christians and evangelicals will agree with the major doctrines that belong in tier 1, but to a Baptist baptism will usually be in tier 2, for others, it might be in tier 3. Some place Dispensationalism or the Reformed version of predestination in tier 2, others in tier 3. You see the difficulty.
But I think this difficulty will be inherent in any structure like this.
It does at least allow one to explain where they fall on the theological spectrum simply by stating where they think a particular doctrine belongs.
So while the system is not fool-proof, it does make more distinction than simply “essential” and “non-essential.”