If you believe that all came originally from the One and that in the fullness of time all things in Christ are gathered together in one, then as a consequence the two paths do meet at the end as Blake claimed. We can put this in a more properly theological context with Blake's expressed response to the calvinistic doctrine of Double Predestination.
Double Predestination contains as its lower half the grim old notion of Hell that has probably done as much as anything else in theology to discredit the Christian faith in the eyes of the modern world. Calvin taught the hoary old superstition that most of the world's population are destined to live without Christ and to die and move on to eternal torment; a lucky few have a happier destiny. The lucky few included Calvin of course and his friends, especially his obedient friends. In contrast Origen, perhaps Paul, and surely Blake believed in single predestination: the two streams converge at the end.
Blake expended an enormous amount of his creative energy combating Double Predestination. He heaped scorn upon scorn on the calvinistic God who curses his children. His break with Swedenborg followed his discovery that Swedenborg was a "Spiritual Predestinarian, more abominable than Calvin's". He later lamented over him and called him the "Samson, shorn by the Churches".
In 'Milton' Blake ironically inverted the calvinistic categories of 'elect' and 'reprobate'. With incredible elegance he used Jesus' words on Calvin like a two edged sword. He simply pronounced on behalf of Christ the obvious truth, as if to say, "Calvin, your doctrine is of the world, and your first shall be last in my kingdom."
Double Predestination is a consequence of a more fundamental error of Rahab, the whore of Babylon, the organized Church, "Imputing sin and righteousness to individuals". Blake addressed that error with his doctrine of states, which we look at in a moment.
In MHH Blake examined most directly the conventional idea of Hell and pronounced it a delusion of a certain type of mind. In Vision of the Last Judgment (Erdman 552-566) he gave his straightforward views about the meaning of the biblical Hell. Again in 'Jerusalem', "What are the Pains of Hell but Ignorance, Bodily Lust, Idleness & devastation of the things of the Spirit?"
However the conventional Hell does seem to have some biblical basis: Isaiah 66.24, Mark 9.43ff; Matthew 25.41 provide examples. How do you deal with all those scriptures? In the first place Blake felt perfectly free to discount anything in the Bible that he found incongruent with his Vision, at least to discount its conventional meaning. The immediate experience always exercised authority over anything second hand. The inerrancy of scripture, another of the Five Fundamentals, meant just about as much to him as Double Predestination.
In the second place, although the doctrine of hell has most often been used as a means of anathematizing those with whom one disagrees, there are certainly more creative ways to deal with it. Blake chose one of these, what he called the doctrine of states. In a conversation with the "seven Angels of the Presence" Milton is told by Lucifer: "We are not individuals but states... Distinguish therefore states from individuals in those states."