Mathematicians say life is like a line segment drawn from two point, from point B to point D.
What is point B to point D
It's from point of Birth(B) to point of Death(D).
So life starts from the moment we are born(B) until the day we die(D).
But in the middle of B(brith) and D(death) is a mysterious C.
What is C then? It's Christ.
If we put Christ in the middle of our life(brith-christ-death) our life will not end at D but extend to E.
What is E? It's External life
So all those who put Christ in the middle of their life have external life after death. But those who do not put Christ in the middle of their lives don't have external life after death, but they have F(fire).
Therefore the mathematical equation or definition of life for Christians is
B+C+D=E, brith+christ+death=External life
And the mathematical equation or definition of life for unbelievers is
(B-C) +D=F, brith-christ+death=fire
Conclusively any one that avoids C must surely lose E.
For further explanation and scriptures reference contact me.