What enables sinners to ‘transfer’ from ‘being found in Adam’ to being ‘found in Christ’?

Having read an article in the British November 2024 *Evangelical Times* newspaper on this question, I was heartily in agreement with it till halfway through, thus giving rise to my question. Very briefly, the writer clearly showed from scripture that we are all doomed to fall under God’s judgment unless our union with Adam changes to union with Christ (Romans 5:14). But then I was troubled to read an interpretation of that chapter ***claiming we are “saved through the obedience of Christ.”*** The writer subscribes to the *Westminster Confession of Faith* that this was Christ perfectly keeping the Law on our behalf. (XIX.5 & 6) Yet the writer then admitted that: > [Many Christians] “still find the pull of legalism to be powerful… Is > my Christian living up to standard? Am I doing well enough to remain > on track for heaven?” *Evangelical Times*, article [‘Joined to the wrong man’](https://www.evangelical-times.org/joined-to-the-wrong-man/) p.10, Vol. 58 No.11 He says such questions are inapplicable as it is who we are united to that determines eternal destinies – and that is true – but my question is, What ***enables*** anyone to be transferred from being united to Adam to Christ? (I am not asking *whether* we are joined to Adam - this question is for those in the Reformed Protestant category, for whom that is a given.) I thought Romans chapter 5 spoke of our “being justified ***by his blood***… reconciled ***by the death of his Son***… saved ***by his life***” (vs. 9-10). When it speaks of obedience, it is Christ having been ***“obedient unto death, even the death of the cross”***, surely? **Is there anywhere in the entire Bible that states we have union with Christ through his obedience to the Law?** Yet if people believe that, is it no wonder they get pulled into legalistic doubts?