The ultimate purpose of our existence is to glorify God!
God said “I have created him for my glory” (Isaiah 43:7). God was talking specifically to Israel (see the preceeding verses) but He made it clear that this actually applies to any child of God, in a broader sense, when He said “Even every one that is called by my name”.
Full context of Isaiah 43:6-12
I will say to the north, Give up; and to the south, Keep not back: bring my sons from far, and my daughters from the ends of the earth; Even every one that is called by my name: for I have created him for my glory, I have formed him; yea, I have made him. Bring forth the blind people that have eyes, and the deaf that have ears. Let all the nations be gathered together, and let the people be assembled: who among them can declare this, and shew us former things? let them bring forth their witnesses, that they may be justified: or let them hear, and say, It is truth. Ye are my witnesses, saith the LORD, and my servant whom I have chosen: that ye may know and believe me, and understand that I am he: before me there was no God formed, neither shall there be after me. I, even I, am the LORD; and beside me there is no saviour. I have declared, and have saved, and I have shewed, when there was no strange god among you: therefore ye are my witnesses, saith the LORD, that I am God. Isaiah 43:6-12
Whatever we do, we should be doing it to bring God glory. This includes the most simplest of things such as eating and drinking.
Whether therefore ye eat, or drink, or whatsoever ye do, do all to the glory of God. 1 Corinthians 10:31
People today, both Christian and non-Christian, for the most part, have this all wrong in their heads. The non-Christian believes generally that the end of all being, the purpose of their existence, is their own happiness. Christians also generally have a similar mindset only they tend to believe, in a twisted way, that God is there for their own pleasure. They have lost sight or have never seen that in truth God created us for His good pleasure. It is not the other way around…
For by him were all things created, that are in heaven, and that are in earth, visible and invisible, whether they be thrones, or dominions, or principalities, or powers: all things were created by him, and for him: And he is before all things, and by him all things consist. Colossians 1:16-17
Blessed be the God and Father of our Lord Jesus Christ, who hath blessed us with all spiritual blessings in heavenly places in Christ: According as he hath chosen us in him before the foundation of the world, that we should be holy and without blame before him in love: Having predestinated us unto the adoption of children by Jesus Christ to himself, according to the good pleasure of his will, To the praise of the glory of his grace, wherein he hath made us accepted in the beloved. In whom we have redemption through his blood, the forgiveness of sins, according to the riches of his grace; Wherein he hath abounded toward us in all wisdom and prudence; Having made known unto us the mystery of his will, according to his good pleasure which he hath purposed in himself: That in the dispensation of the fulness of times he might gather together in one all things in Christ, both which are in heaven, and which are on earth; even in him: In whom also we have obtained an inheritance, being predestinated according to the purpose of him who worketh all things after the counsel of his own will: That we should be to the praise of his glory, who first trusted in Christ. Ephesians 1:3-12
When it comes down to it, we are really not ‘needed’ by God for anything but He has chosen to redeem us back to our original purpose regardless, so as to bring Him glory.
For as I passed by, and beheld your devotions, I found an altar with this inscription, TO THE UNKNOWN GOD. Whom therefore ye ignorantly worship, him declare I unto you. God that made the world and all things therein, seeing that he is Lord of heaven and earth, dwelleth not in temples made with hands; Neither is worshipped with men's hands, as though he needed any thing, seeing he giveth to all life, and breath, and all things; And hath made of one blood all nations of men for to dwell on all the face of the earth, and hath determined the times before appointed, and the bounds of their habitation; That they should seek the Lord, if haply they might feel after him, and find him, though he be not far from every one of us: For in him we live, and move, and have our being; as certain also of your own poets have said, For we are also his offspring. Forasmuch then as we are the offspring of God, we ought not to think that the Godhead is like unto gold, or silver, or stone, graven by art and man's device. And the times of this ignorance God winked at; but now commandeth all men every where to repent: Because he hath appointed a day, in the which he will judge the world in righteousness by that man whom he hath ordained; whereof he hath given assurance unto all men, in that he hath raised him from the dead. Acts 17:23-31
This is where we bring the conversation full circle back to Isaiah 43:6 and 7 where God said “I have created him for my glory…Even every one that is called by my name”.
Glorify as per Webster’s 1828:
GLO'RIFY, verb transitive [Latin gloria and facio, to make.]
1. To praise; to magnify and honor in worship; to ascribe honor to, in thought or words.
All nations whom thou hast made shall come and worship before thee, O Lord; and shall glorify thy name. For thou art great, and doest wondrous things: thou art God alone. Psalm 86:9-10
God is glorified, when such his excellency, above all things, is with due admiration acknowledged.
2. To make glorious; to exalt to glory, or to celestial happiness.
3. To praise; to honor; to extol.
4. To procure honor or praise to.