Jesus has made the life of believers in Him as certain as His own. As sure as the Head lives the members live also. If Jesus has not risen from the dead, then are we dead in our sins; but since He has risen, all believers are risen in Him. His death has put away our transgressions and loosed the bonds which held us under the death sentence. His resurrection proves our justification: we are absolved, and mercy saith, “The Lord hath put away thy sin, thou shalt not die.”
Jesus has made the life of His people as eternal as His own. How can they die as long as He lives, seeing they are one with Him? Because He dieth no more, and death hath no more dominion over Him, so they shall no more return to the graves of their old sins but shall live unto the Lord in newness of life. O believer, when, under great temptation, thou fearest that thou shalt one day fall by the hand of the enemy, let this reassure thee. Thou shalt never lose thy spiritual life, for it is hid with Christ in God. Thou dost not doubt the immortality of thy Lord; therefore, do not think that He will let thee die, since thou art one with Him. The argument for thy life is His life, and of that thou canst have no fear; wherefore rest in thy living Lord.
[from Faith’s Checkbook by Charles H. Spurgeon]