I found a short piece by Al Mohler on ranking the importance of controversies.
Mohler wrote this:
Third-order issues are doctrines over which Christians may disagree and remain in close fellowship, even within local congregations. I would put most of the debates over eschatology, for example, in this category. Christians who affirm the bodily, historical and victorious return of the Lord Jesus Christ may differ over timetable and sequence without rupturing the fellowship of the church. Christians may find themselves in disagreement over any number of issues related to the interpretation of difficult texts or the understanding of matters of common disagreement. Nevertheless, standing together on issues of more urgent importance, believers are able to accept one another without compromise when third-order issues are in question.
He doesn't mention it specifically, but Mohler obviously believes the bodily, historical and victorious return of Christ must be either a second or first order doctrine. I would say it is a first order doctrine because to deny it leads to many other first order problems.
What would you do with a man who denies the bodily, historical and victorious return of Christ in the future? Is that someone you can call a Christian but you just can't have fellowship with? (a second order doctrine) Or do you stand in doubt of their salvation at all? (a first order doctrine?)