Ephesians 4:8-10
[8] Wherefore he saith, When he ascended up on high, he led captivity captive, and gave gifts unto men. [9] (Now that he ascended, what is it but that he also descended first into the lower parts of the earth? [10] He that descended is the same also that ascended up far above all heavens, that he might fill all things.)
1 Corinthians 15:28
[28] And when all things shall be subdued unto him, then shall the Son also himself be subject unto him that put all things under him, that God may be all in all.
How can this be when there is an outer darkness reserved??
I answered this already. It is about the knowledge of His glory. His knowledge will fill all things. Even the rocks will experience His glory.