Has the day of our death been predetermined? Are we powerless to change it? Has God specified a time for our death and the number of our days?
You can read about predestination, like in Ephesians 1, and all it means is that something has been predetermined…or been determined ahead of time. This doesn’t mean we don’t have free will and that we won’t be responsible for our actions and that we won’t reap what we sow. No, we suffer  the consequences or reap the blessings according to our actions. I cannot hope to fully explain the tension that exists between free will (John 3:16) and predestination (Eph 1). I only know that both are true but I don’t know how they are both true at exactly the same time. That should not surprise anyone because who can fully know the mind of God since His ways are beyond finding out. Here are a few reasons I can say that with biblical authority:
Job 11:7 “Can you find out the deep things of God? Can you find out the limit of the Almighty?”
Job 36:26a “Behold, God is great, and we know him not.”
Ecclesiastes 3:11 “He has made everything beautiful in its time. Also, he has put eternity into man’s heart, yet so that he cannot find out what God has done from the beginning to the end.”
Romans 11:33 “Oh, the depth of the riches and wisdom and knowledge of God! How unsearchable are his judgments and how inscrutable his ways!”
I could have added dozens more but I think you get the idea. The way God thinks is nothing close to the way we think. When we can’t fully explain the ways of God we must accept it anyway. Just because I can’t explain how gravity works doesn’t mean it isn’t so and just because I can’t understand something doesn’t mean it’s not true but what about the day of our death? Is the day of our death predetermined? Is it down even to the hour and the second? Are all of our days established before we are even born? These are all great questions and the answers can be found in the Scriptures but the explanations; that I can’t help you with. That’s why He is God and we are not!
Number Our Days
Biblical wisdom has always been that we are like the grass in the field and so we should learn to number our days; that is we should make every day count. Maybe that’s what the Psalmist meant when he wrote “teach us to number our days, that we may present to You a heart of wisdom” (Psalm 90:12). He actually asked “Show me, LORD, my life’s end and the number of my days; let me know how fleeting my life is” (Psalm 39:4) so God “teach us to number our days that we may get a heart of wisdom.” When the religious leaders tried to take Jesus by force to have Him arrested He said “My time has not yet come, but your time is always here” (John 7:6) so God knows all about the days of our life and all of the affairs and schemes of men and we cannot change what God has sovereignly ordained ahead of time.
Our Days Determined
Every one of our days, believe it or not, have already been determined and even more amazing, they have been numbered before we were even born. Job knew this when he said “Man who is born of a woman is few of days and full of trouble. He comes out like a flower and withers; he flees like a shadow and continues not. And do you open your eyes on such a one and bring me into judgment with you? Who can bring a clean thing out of an unclean? There is not one. Since his days are determined, and the number of his months is with you, and you have appointed his limits that he cannot pass” (Job 14:1-6). Imagine that! We cannot go one day beyond the day he has appointed for us to live. We have limits to our life. We cannot even “go one day beyond” them. The fact is that God’s “eyes saw my unformed substance; in your book were written, every one of them, the days that were formed for me, when as yet there was none of them” (Psalm 139:16). Not only are the very days of our life established “even the hairs of your head are all numbered” (Matt 10:30).
God’s Sovereignty and Our Days
Even though our days are appointed for how long we will live on this earth God tells us “if you walk in obedience to me and keep my decrees and commands as David your father did, I will give you a long life” (1 Kings 3:14). This is why obedience  is so important and we are commanded to “Honor your father and your mother, so that you may live long in the land the Lord your God is giving you” (Ex 20:12). We do know that we’ve only got one life and only a short amount of time to get right with God because “Just as people are destined to die once, and after that to face judgment” (Heb 9:27). God gives us all a choice…either believe in Christ and inherit eternal life (John 3:16) or reject Christ and have His wrath abiding on us for all time (John 3:36b). He tells us to make a choice today:
“See, I set before you today life and prosperity, death and destruction. For I command you today to love the Lord your God, to walk in obedience to him, and to keep his commands, decrees and laws; then you will live and increase, and the Lord your God will bless you in the land you are entering to possess. But if your heart turns away and you are not obedient, and if you are drawn away to bow down to other gods and worship them, I declare to you this day that you will certainly be destroyed. You will not live long in the land you are crossing the Jordan to enter and possess. This day I call the heavens and the earth as witnesses against you that I have set before you life and death, blessings and curses. Now choose life, so that you and your children may live” (Duet 30:15-19).
You have a choice to make. Repent and trust in Christ or face God’s wrath with no end in sight (Rev 20:11-15). He tells us “Today, if you hear his voice, do not harden your hearts” (Heb 3:7) and “In the time of my favor I heard you, and in the day of salvation I helped you. I tell you, now is the time of God’s favor, now is the day of salvation” (2 Cor 6:2). Tomorrow may be too late for if Christ returns and you are not saved, you are condemned for all time but if you repent and trust in the Savior, you will be saved. Let me close with the way Daniel the Prophet puts it: “at that time your people—everyone whose name is found written in the book—will be delivered. Multitudes who sleep in the dust of the earth will awake: some to everlasting life, others to shame and everlasting contempt. Those who are wise will shine like the brightness of the heavens, and those who lead many to righteousness, like the stars for ever and ever” (Dan 12:1a-3). You are free to choose but choose you must, for no choice is a no-choice because Christ said “He who is not with me is against me and he that is not against us is for us” (Matt 12:30).
Take a look at these other great Christian answers: Bible Answers to Questions 
Resource – Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), copyright © 2001 by Crossway, a publishing ministry of Good News Publishers. Used by permission. All rights reserved.