Shedd, Hodge, and Warfield: the boundary already crossed
From Sovereign Grace and the Scope of Election: A Comparative Examination of Attainment Theology and Grace Theology, with Particular Attention to the Question of Whether God's Elect Are Found Among All Nations and Religions
That extension is not novel. William G. T. Shedd, among the most rigorous Reformed dogmaticians of the nineteenth century, argued openly (Dogmatic Theology; Calvinism: Pure and Mixed) that the Holy Spirit, who is confined to no ordinary channel, may regenerate some among the unevangelized apart from the written word, and he defended the Westminster clause as deliberately leaving that door open. Charles Hodge, no sentimentalist, ventured in his Systematic Theology that the number of the finally lost, compared with the whole company of the saved, would be relatively small. B. B. Warfield pressed the same optimism in his essay "Are They Few That Be Saved?", arguing that the fewness sayings of the Gospels describe the visible situation of Christ's own generation, not the final census of the redeemed. None of these men were inclusivists, and none surrendered the necessity of Christ's atonement for every saved soul. They were particularists who refused to make God's regenerating power a function of missionary geography. This document stands in that line and goes one deliberate step further along it.