In it, Rev. Campbell makes some excellent points against the attitude of denominationalism--the idea that the visible church consists of lots of legitimate denominations that happily coexist but aren't in formal communion with each other under binding councils. He rightly and clearly points out that this concept has no place in presbyterianism:
The concept of “denominations” is essentially un-Presbyterian and un-scriptural and brings out an essentially schismatic way of thinking if it is just accepted at face value. The concept is certainly foreign to the principles of the Reformed Church of Scotland and its clear teaching concerning the indivisibility of the visible Church.
A “concern about the number of competing denominations in Scotland” ought therefore to be a concern about the concept of denominationalism itself. There is no place in biblical Presbyterianism for more than one visible Church body.
The article is particularly focused on the situation in Scotland, where, in addition to the general principle that the church of Christ is to be one, there is an established law that designates one Church of Scotland as the official church, thus negating the possibility of multiple legitimate denominations within the nation.
Rev. Campbell points out clearly the implications of the fact that the church is called to be one in formal unity and that there can be, by law, only one national church in Scotland. These facts imply that only one denomination in Scotland can claim to be the de jure legitimate church in Scotland, and all other denominations in Scotland lack de jure legitimacy:
True Scottish Presbyterians ought to be extremely concerned that their “denomination” has a legitimate and constitutional right to exist. A true right to exist is the right of the Scottish Reformation Church by law established to exist and if it can be proven, it per se denies and disqualifies all other “competing denominations” from claiming that right.
Rev. Campbell boldly and clearly makes the claim that it is the Free Presbyterian Church of Scotland which is the only true representative of the national Church of Scotland, and thus the only church that can claim de jure legitimacy in Scotland.
Although Rev. Campbell is focused on the church in Scotland, I would add (what is implicit in his article) that the same principles apply on the international level as well. There is only one church of Christ. Denominational separation between legitimate de jure churches is an un-presbyterian concept. Therefore, whenever denominations are divided, including on the international level, we must examine their claims to see which one has legitimacy and join ourselves to it as far as we are able to do so, and avoid, as far as we are able, union with illegitimate denominations. Only this attitude preserves a consistent biblical presbyterianism.