Convince the High Confessor to meet with you is a quest objective in the mission Reformation in Fallout 4: Far Harbor.
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Walkthrough[edit]
With the holotape, Martin's New Age in your possession, it is time to return to the Nucleus. It helps greatly having completed at least some parts of What Atom Requires, specifically, Witch Hunt.
You can mostly find Confessor Tektus in his chamber within the Vessel inside the Nucleus.
Talk with him and show him the holotape that you got from DiMA. He will be a bit startled but then tell you to play the tape.