Oikos and Oikia.
1878 128 On the whole, in spite of authorities, I am disposed to think that oikos is the house viewed from outside as an object set before us, oikia from inside; oikos the building as such, the temple always, so a family, or lineage metaphorically. It is very often merely a difference of conception in the writer. If I think of the house as a building to which I came, I should say, oikos, if I was going in to a set of people in it, or having to do with the house inside of it, not materially, but as containing, I should say, oikia. We have a striking example, how near they run together, and yet have a different sense: in 1 Corinthians 1:16 oikos of Stephanas, the family looked at objectively from without; in 1 Corinthians 16:15, oikia. The material house as from without was not the firstfruits, but the household as a whole which was so. What seems a difficulty is the end of sermon on the Mount, building the house on a rock. (Matt. 7:24-25; Luke 6:48-49: as far as I find, it is always thus, oikodomesen oikian.) I think oikia is the whole concern the builder had in his mind for his habitation, a dwelling with his family, which was of course a house. Hence "go not from house to house," is oikia, though they might from oikos to oikos. Cf. Matthew 5:15; Philippians 4:22, and more strongly Matthew 10:12-14, Matthew 13:51; John 4:53. In Luke 10:5, we have both. They go into the oikian or dwelling containing the family, and say, Peace be to this house, oikoi, an object before their minds as one thing. They brake bread, kat oikon; and so ten kat oikon auton ekklesian meeting there, not in the household. See Acts 2:46, Acts 5:42, Acts 8:3, Acts 20:20. So the blessing comes as the peace on the oikon, Luke 19:9. In Matthew 12:25, oikia kat heautes, in Luke 11:17, oikos epi oikon. Here in Luke oikia would not do; it is a single whole thing, not collective as in Matthew: oikia would have been too intimate.