One of the earmarks of false teachers is the claim the words mean what they say they mean, not what they mean in other places. Thus words have no meaning. This is a tool of the trade of making scripture to no effect.
The next tool in the tool box of false teachers is to prove "A" and then simply claim "B" has been proven.
Next they make distinctions without a difference, saying "in Christ" does not appear in the passage. But in verse 26 we see that the Spirit helps our weaknesses, and we are sealed "in Christ" with that Spirit. Who are those who are called according to His purpose, those not in Christ or those in Christ? The facts are in evidence.
God does not place people who have yet to be created in Christ. This view redefines creation as happing before creation. A logical absurdity. But if words have no meaning, then no problem!
Does foreknew mean individually chosen? Of course not. It means something known beforehand, such as His predetermined plan of redemption including the corporately elected target group, those whose faith God credits as righteousness.
We are called through the gospel during our lives. Therefore no one is called according to His purpose until they have heard and affirmatively responded to the gospel. And therefore, the redemption plan included the feature that anyone spiritually placed in Christ, the saints of verse 27, would be predestined to two things: being conformed to the image of God and make Christ the first born of many brothers. So all the saints in Christ are born again after the first born Christ, otherwise someone else, say Abraham, would be the first born. But no, Abraham had to wait for Christ to be made perfect in Christ just as Hebrews says.
Lets look at the package of Romans 8:29 and 30. Paul is describing the package of God's actions applicable to each individual placed spiritually in Christ, becoming one of the "saints" of verse and one of the "called according to His purpose" of verse 28.
First they were foreknown, refering to God choosing Christ as His Redeemer, and therefore the target group of His redemption plan was chosen corporately. Next, because His redemption plan is unfolding, continuing action, God is continuing to place people into His foreknow target group, the "body of Christ. The plan is that anyone spiritually placed in Christ will be predestinated to be conformed to the image of Christ and adopted as a child of God. Therefore our bodily resurrection is predestinated. And this is also still unfolding, as each new believer is spiritually placed in Christ, they are being predestinated to be conformed and resurrected.
Now who exactly was predestinated? Whoever was spiritually placed into the body of Christ. No one was predestinated that has not been placed into the body of Christ.
And then speaking of these who have been placed into the body of Christ, Paul continues with the package. He also called them, and this refers to those whose faith He credits as righteousness, so again this is an ongoing process applicable to everyone spiritually placed in Christ. And next, when we are spiritually placed in Christ, we undergo the circumcision of Christ whereby we receive the justification provided by Christ's sacrifice on the cross. And finally, since we are spiritually in Christ we are spiritually glorified. That completes the package I call positional sanctification where we are transferred from the realm of darkness into the kingdom of God.
As far as 1 Cor 2:7, yes the grammar points to "wisdom" but using the context of verse 8, it appears that the wisdom was none other that Jesus Christ our Lord.
Again Ephesians 1:5 does not say we were chosen because we were predestined, it says we were predestined because we were chosen. Here is a snippet from a published source:
"It is better to view God’s act of election as being expressed in the predestination of
the elect, so that the primacy of election remains without diminishing the importance
of predestination. Therefore the participle is modal and the two concepts are
simultaneous acts of God, without temporal sequence"