Immortality comes only through obedience to God’s word and is bestowed as a gift from God at Christ’s second coming. This is not to say that it is of works that we are saved. Obedience is the fruit of faith, salvation is the gift of faith.
1 Corinthians 15:21-22
For since by man came death, by man came also the resurrection of the dead. For as in Adam all die, even so in Christ shall all be made alive.
1 Corinthians 15:51-55
Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed, In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed. For this corruptible must put on incorruption, and this mortal must put on immortality. So when this corruptible shall have put on incorruption, and this mortal shall have put on immortality, then shall be brought to pass the saying that is written, Death is swallowed up in victory. O death, where is thy sting? O grave, where is thy victory?
Put not your trust in princes, nor in the son of man, in whom there is no help. His breath goeth forth, he returneth to his earth; in that very day his thoughts perish.
For the living know that they shall die: but the dead know not any thing, neither have they any more a reward; for the memory of them is forgotten. Also their love, and their hatred, and their envy, is now perished; neither have they any more a portion for ever in any thing that is done under the sun.
Whatsoever thy hand findeth to do, do it with thy might; for there is no work, nor device, nor knowledge, nor wisdom, in the grave, whither thou goest.
1 Timothy 6:15-16
Which in his times he shall shew, who is the blessed and only Potentate, the King of kings, and Lord of lords; Who only hath immortality, dwelling in the light which no man can approach unto; whom no man hath seen, nor can see: to whom be honour and power everlasting. Amen.
2 Timothy 1:10
But is now made manifest by the appearing of our Saviour Jesus Christ, who hath abolished death, and hath brought life and immortality to light through the gospel:
1 John 5:11-12
And this is the record, that God hath given to us eternal life, and this life is in his Son. He that hath the Son hath life; and he that hath not the Son of God hath not life.