"having predestined us unto 'son-placement' [divine-adoption-OF-SONS]"... (which is not the same kind of "adoption" WE think of, where a child outside of the family is brought into your family... but where the "full-grown-son [of one's own]" is bestowed the "full rights to act in his father's name" which is what Jesus had [note the words of the Father at His/Jesus' baptism]... and we have in a LEGAL/positional sense [ONLY by means of our "connection with Christ"] the moment we are "born [born-again/-from-above]" even as "new-born babes in Christ"--that is, in a LEGAL/positional sense... that is never severed... and which will be operative in a fuller sense once Romans 8:23 takes place [at "our Rapture" point in time])... So this is "eternal" and not a temporary, "iffy" thing.
PERMANENT.
"having foreordained [to predetermine, foreordain] us to 'the adoption of sons [G5206 - huiothesian ('son-placement')]' through Jesus Christ to Himself, according to the good pleasure of His will" Eph1:5
...which I believe is related to what is stated in Romans 8:23 (though we possess it in a LEGAL/POSITIONAL sense, even *NOW*), which says, "And not only so, but also we ourselves, having the first-fruit of the Spirit, we also ourselves in ourselves do groan, adoption [G5206 - huiothesian] expecting/awaiting -- the redemption of our body" (which I believe is related to what is said in Rev12:5, "And she brought forth a male [G730 -arsen/arren] son [G5207 - huion], who is about to shepherd all the nations with a rod of iron; and her child was caught up [G726 - hērpasthē/harpazo] to God, and to His throne" and where v.13 said, "[the woman] which HAD BROUGHT FORTH the male [G730 - arsena/arren]" (i.e. HAD BROUGHT FORTH being "past tense" from this mid-trib point in the chronology; note: no word "child" is in THIS verse, v.13)]
IOW, I believe this is why Paul said (to "the Church WHICH IS HIS BODY"/same persons ^ at top)… in Romans 16:20, "And the God of peace will crush/bruise Satan UNDER YOUR FEET *IN QUICKNESS [NOUN]*" (the same "IN QUICKNESS [NOUN]" time period that IS the "future" aspects of the Revelation, FROM 4:1 TO [7-yrs later-]Rev19/His "RETURN" to the earth; and the same time period as the "AVENGE *IN QUICKNESS [NOUN]*" of Lk18:8 [this aspect, unfolding on the earth])