Eldmessutangi (e. Fire Sermon Point) is the point where an encroaching lava branch flowing from the voluminous 1783 Laki crater eruptions miraculously stopped. The relieved residents of the village credited the local pastor, Rev. Jón Steingrímsson (and presumably his God!), with their deliverance. He had previously preached his so-called fire sermon, which must have been the ultimate fire-and-brimstone sermone with lava and tephra raining down on his parish.
A more mundane explanation is that the lava was stopped by the Skaftá river. Regardless of which theory you subscribe to, the fact remains that during the sermon the lava stopped just to the west of Systrastapi, and the lava point marking its terminus can still be seen to this day.