I don't think that he does. While we are under sentence of death, I believe many die prematurely due to their own or others actions. For example, a horrific, fatal car crash caused by a drunk or distracted driver is the fault of the driver, not God. I believe the Bible teaches we can extend or shorten our lives by our own actions and decisions. Moses told the Israelites: "I take the heavens and the earth as witnesses against you today that I have put life and death before you, the blessing and the curse; and you must choose life so that you may live, you and your descendants, by loving Jehovah your God, by listening to his voice, and by sticking to him, for he is your life and by him you will endure a long time in the land that Jehovah swore to give to your forefathers, Abraham, Isaac, and Jacob." (Deuteronomy 30:19,20
What do you think?
Not being able to add days to your life may refer to the 120-year limit God eventually specified (which has remained true with very few exceptions and no extreme exceptions) -essentially so that he did not have to be frustrated with man any longer than absolutely necessary.
Gen 6:3 And the LORD said,
My spirit shall not always strive with man, for that he also is flesh: yet
his days shall be an hundred and twenty years.
It would not be impossible for "God" -a being able to number every hair on every head -to determine the exact time of every death -but that is not to say there would be reason to do so.
The following might be true only from our perspective -but perhaps God only specifies that which is absolutely necessary.
Ecc 9:11 I returned, and saw under the sun, that the race is not to the swift, nor the battle to the strong, neither yet bread to the wise, nor yet riches to men of understanding, nor yet favour to men of skill; but
time and chance happeneth to them all.
The exact times of the deaths of certain people are specified in the bible -most notably Christ...
Acts 2:23 Him, being
delivered by the determinate counsel and foreknowledge of God, ye have taken, and by wicked hands have crucified and slain:
...but perhaps not every last person.
If given the opportunity, it would not be impossible for man to eventually reverse-engineer himself to the point of reversing the changes made which limited his lifespan -or even to even to eventually design an invulnerable body (not that it would help previous humans) -but given the timeline of events outlined in the bible, such things will be made available before we are able to accomplish them ourselves.
If we neared such abilities -and God decided it was not a good idea -he could set us back as he did at the tower of Babel -which was to prevent us from accomplishing anything we could imagine while we lacked the discipline and understanding to prevent chaos and catastrophe. What is specifically written, however, is that God will again prevent us from doing what we otherwise would -namely destroying all flesh by our warfare (which would likely have happened much sooner if speech was not confused at Babel) -after which will be a process of bringing many to final perfection and giving them invulnerable bodies with extreme creative power and a much more direct interface.
Gen 3:22 And the LORD God said, Behold, the man is become as one of us, to know good and evil: and now,
lest he put forth his hand, and take also of the tree of life, and eat, and live for ever:
Gen 3:23
Therefore the LORD God sent him forth from the garden of Eden, to till the ground from whence he was taken.
Gen 3:24 So
he drove out the man;
and he placed at the east of the garden of Eden Cherubims, and a flaming sword which turned every way, to keep the way of the tree of life.
Job 14:5 Seeing
his days are determined, the number of his months are with thee,
thou hast appointed his bounds that he cannot pass;
Gen 11:6 And the LORD said, Behold, the people is one, and they have all one language; and this they begin to do: and
now nothing will be restrained from them, which they have imagined to do.
Gen 11:7 Go to,
let us go down, and there confound their language, that they may not understand one another's speech.
Mat 24:21 For
then shall be great tribulation, such as was not since the beginning of the world to this time, no, nor ever shall be.
Mat 24:22 And
except those days should be shortened, there should no flesh be saved: but for the elect's sake
those days shall be shortened.
Mic 4:3 And he shall judge among many people, and rebuke strong nations afar off; and they shall beat their swords into plowshares, and their spears into pruninghooks: nation shall not lift up a sword against nation
, neither shall they learn war any more.
Php 3:21 Who
shall change our vile body, that it may be fashioned like unto his glorious body, according to the working
whereby he is able even to subdue all things unto himself.
1Co 15:22 For as in Adam all die, even so in Christ
shall all be made alive.
1Co 15:23 But
every man in his own order: Christ the firstfruits; afterward they that are Christ's at his coming.
1Co 15:24 Then cometh the end, when he shall have delivered up the kingdom to God, even the Father; when he shall have put down all rule and all authority and power.
1Co 15:25 For he must reign, till he hath put all enemies under his feet.
1Co 15:26
The last enemy that shall be destroyed is death.
Rev 20:12 And
I saw the dead, small and great, stand before God; and the books were opened: and another book was opened, which is the book of life: and the dead were judged out of those things which were written in the books, according to their works.
Rev 20:13 And the sea gave up the dead which were in it; and death and hell delivered up the dead which were in them: and they were judged every man according to their works.
Rev 20:14
And death and hell were cast into the lake of fire. This is the second death.
Rev 20:15 And
whosoever was not found written in the book of life was cast into the lake of fire.
1Co 3:13
Every man's work shall be made manifest: for the day shall declare it,
because it shall be revealed by fire; and the fire shall try every man's work of what sort it is.
1Co 3:14 If any man's work abide which he hath built thereupon, he shall receive a reward.
1Co 3:15
If any man's work shall be burned, he shall suffer loss: but he himself shall be saved; yet so as by fire.