Salvation "in Christ".
This simply means... that Jesus has accomplished righteousness by dying sinless, and he has offered the eternal sacrifice for the sin of the world by shedding His blood and dying.
So, God takes ALL that, which Christ has accomplished, and gives it to us as a "GIFT".... when we God our Faith in Christ.
The "Gift of Salvation"
The "Gift of Righteousness'"
The "Gift of Eternal Life"
We can't DO that for ourselves............we can only RECEIVE from God what Christ has provided 2000 yrs ago, and when we receive this "Gift of Salvation" then we have it., and this is to become "born....again", Spiritually, as a "new Creation" "In Christ".
We, the born again... now ETERNALLY exist spiritually joined to God and Christ.....and that is the "new Birth"... that is.. to have become..
"Translated from Darkness.....TO LIGHT"...
See that "LIGHT"?
That Light is the Kingdom of God.. as "God exists IN LIGHT", and "Jesus is the LIGHT of the World", and all the born again CHRISTians, are born again as "Children of THE LIGHT".