In or out?

No, this isn’t about the EU vote.  
Something far more enduring:
John 3:36  "He who believes in the Son has eternal life; but he who does not obey the Son will not see life, but the wrath of God abides on him."

There’s a finality here.
A simplicity.
A clarity, a distinction.
You have eternal life, or you abide in wrath.
You are in Christ, or you are in Adam.
Romans 5:12  "Therefore, just as through one man sin entered into the world, and death through sin, and so death spread to all men, because all sinned-- 
… 18  …, even so through one act of righteousness there resulted justification of life to all men." 

However you might divide humanity – from a Gospel point of view – this is possibly the clearest and most relevant.
It speaks to where people are, and how to reach them.
How many Gospels are needed?
Look at the Apostles - was theirs a uniform culture?
Those cultures were even more isolated/distinct than ours - they didn’t have mass communication.
This is the sum of the Gospel to be preached to every creature:
John 3:17  "For God did not send the Son into the world to judge the world, but that the world might be saved through Him. 
18  "He who believes in Him is not judged; he who does not believe has been judged already, because he has not believed in the name of the only begotten Son of God."
Believer, or judged.
Christ, or Adam.

Clarity for the unbeliever, comfort for the Church, for -
John 3:36  "He who believes in the Son has eternal life; but he who does not obey the Son will not see life, but the wrath of God abides on him."
The Christian has life everlasting.

And notice, lovers of Jesus – this is sweet.
It’s your state now:  has eternal life
Even now, you have everlasting life.
Not “shall have it later”, but have it now. 

Do you lack assurance?  How?  Have you read and understood the plain words?
The matter is sealed, 
John 3:33  "He who has received His testimony has set his seal to this, that God is true.”
By God’s Spirit, and it’s signed, sealed, delivered -
2 Corinthians 5:5 “Now He that hath wrought us for the selfsame thing is God, who also hath given unto us the earnest of the Spirit.” 
Ephesians 1:14  “… the earnest of our inheritance until the redemption of the purchased possession, unto the praise of His glory.” 

When God gives a guarantee?             
By the grace of God, when you’re in, you’re in.