I'm pretty sure you don't understand what it means to be in Christ just based off of what you said. Please don't take that as a knock, but rather as a wakeup call.
So much more could be said about how Christ is in His Father and how we are in Christ. Even Christ gave stories about vines and branches being cut off to help illustrate how this works, Paul did too, but I find that it's better if you have something more direct, concrete, and open to less interpretation. Hebrews 3 provides it.
Hebrews 3
12See to it, brothers, that none of you has a wicked heart of unbelief that turns away from the living God.
13But exhort one another daily, as long as it is called today, so that none of you may be hardened by sin’s deceitfulness.
14We have come to share in Christ if we hold firmly to the end the assurance we had at first.