Summing Up means God is taking all of the disconnected separately directed things and bringing them to completion in a sum.
ALL things summed up in Christ. Jesus only. Not Mohammed. Not Abraham. Not Buddha. Not spirit ancestors. Not angels. Not light. Not a shaman. Not a Dalai Lama. Not ourself. Not riches and estates. Not power or might.
Is this offensive or is it maybe a source of comfort? Let's consider what we can read in Ephesians 1:7-15.