Being "in Christ" is part and parcel of the believer's redemption. It has nothing to do with what, in our day, passes for salvation.
Being saved is what God does for those whom he "quickens, calls, and recreates, "in Christ Jesus". See Ephesians 2:1-4; Ephesians 2:10; 2 Cor. 5:17. Most church-members in our day do not even come close to appreciating what is meant by that phrase, "in Christ".
I want us to think about what it means to be "in Christ". Whether you realize it or not, being "in Christ" means having been created as a new creature, in Christ. (Ephesians 2:10). It also means that we are one of those that God loved, before the foundation of the world and who have been or will be called to salvation.
It means that when Christ went to the cross he bore our sins and paid the debt that we could never pay. It means that our eternal circumstance will be in heaven, we shall never receive condemnation....Jesus suffered that for us.
We share in the divine nature by being conformed to the image of Christ by the Holy Spirit that indwells us from the moment we are saved. It means that the old creature that we were because of Adam's nature is dead. Romans 6:6; Romans 8:2,10.
The word of God makes it abundantly clear that those who have not been quickened, recreated and born again, are not "in" Christ.
See Ephesians 2:11-12. Unless and until we, who profess faith in Jesus Christ, really understand, what being "in Christ" really means and how that position really makes a great difference in those who are truly saved, we have missed true salvation.
Let's ask the word of God, what it means to be "in Christ". Look first at Romans 3:24, where we find that we are justified "freely" by his grace through redemption that is "in Christ".