I would love to post the whole context of the quote below, but that would make the post too long. So below is just one example of the teaching of Turretin on the subject of the extraordinary call to the ministry and even forming churches where there's no predecessor(s) available.
XVIII. If today believers, carried by a tempest to the most distant regions of the earth, should be shipwrecked upon the shore among barbarous people, entirely strangers to religion, and pressed by necessity should be compelled to remain there without any hope of returning to their homes, who does not confess that from the law of love they ought to teach the pagans the faith of Christ? And if many of them should perchance be converted, would it not be lawful for them to choose for themselves pastors to constitute a church and provide for its edification and instruction? Would it be better to suffer that light to be extinguished than to establish a ministry for the consolation and salvation of that people, although this could not be done according to the usual order? Thus if perchance it happens in a most severe persecution of a church or province that all the pastors are either entirely destroyed or so scattered that they cannot easily be gathered together or other pastors be obtained elsewhere; in this case would it be more advisable for the believing people to remain without a pastor and without external worship and thus suffer the light of the gospel and all religion to be extinguished than that it should be permitted them to elect and constitute some suitable private person from their own body to feed and teach them, although the received order could not be adhered to? Nay, who does not see that the glory of God and the salvation of believers demands the contrary altogether? No more can it be sought by what right and by what authority and call these things are done than it can be demanded of a citizen what call he has for opposing himself to an inrushing enemy when the leaders are treacherous; or for extinguishing a fire enveloping a house, if others fail. For the case of necessity and the salvation of the republic (which ought to be the supreme law) demands this. It is the same as if I should ask a man what right he had to obey God and to resist Satan. What call he has to procure his own and his neighbor’s salvation. Everyone knows that this is an indispensable necessity.
Turretin, F. (1992–1997). Institutes of Elenctic Theology. (J. T. Dennison Jr., Ed., G. M. Giger, Trans.) (Vol. 3, pp. 221–222). Phillipsburg, NJ: P&R Publishing.
