12 Let us not be frightened at that other death, but let us fear this one. But, what is very grievous, many, through a perverse fear of that other, have fallen into this. It has been said to some, Adore idols; for if you do it not, you shall be put to death: or, as Nebuchadnezzar said, If you do not, you shall be thrown into the furnace of flaming fire. Many feared and adored. Shrinking from death, they died. Through fear of the death which cannot be escaped, they fell into that which they might happily have escaped, had they not, unhappily, been afraid of that which is inevitable.
As a man, you are born— art destined to die. Whither will you go to escape death? What will you do to escape it? That your Lord might comfort you in your necessary subjection to death, of His own good pleasure He condescended to die. When you see the Christ lying dead, are you reluctant to die? Die then you must; you have no means of escape. Be it today, be it tomorrow; it is to be— the debt must be paid. What, then, does a man gain by fearing, fleeing, hiding himself from discovery by his enemy?
Does he get exemption from death? No, but that he may die a little later. He gets not security against his debt, but asks a respite. Put it off as long as you please, the thing so delayed will come at last. Let us fear that death which the three men feared when they said to the king, “God is able to deliver us even from that flame; and if not,” etc. There was there the fear of that death which the Lord now threatens, when they said, But also if He be not willing openly to deliver us, He can crown us with victory in secret.
Whence also the Lord, when on the eve of appointing martyrs and becoming the head-martyr Himself, said, “Be not afraid of them that kill the body, and after that have no more that they can do.” How “have they no more that they can do”? What if, after having slain one, they threw his body to be mangled by wild beasts, and torn to pieces by birds? Cruelty seems still to have something it can do. But to whom is it done? He has departed. The body is there, but without feeling. The tenement lies on the ground, the tenant is gone.
And so “after that they have no more that they can do;” for they can do nothing to that which is without sensation. “But fear Him who has power to destroy both body and soul, in hell fire.” Here is the death that He spoke of when He said, “He that keeps my saying shall never see death.” Let us keep then, brethren, His own word in faith, as those who are yet to attain to sight, when the liberty we receive has reached its fullness.
Source: Tractates on the Gospel of John (New Advent)