Sole Satisfier is a terminology of Christian theology which refers to God as the only one who can satisfy human beings.
The terminology is based on the teachings of St. Thomas Aquinas, known as the universal teacher of the Catholic Church, who said: "God alone satisfies." (Exposition of the Apostles’ Creed 1)
In turn this is based on the Bible: "Come to me all you who labor and are heavy laden, and I will give you rest." (Mt 11: 28); "Only God is good." (Luke 18:19)
It is also based on philosophy or rational thinking, especially in the discussion on happiness and the summum bonum, the greatest good.
Many biblical quotes come together to bring about the Christian belief in God as Sole Satisfier:
Jesus Christ whom Christian theology considers as God says: "Come to me all you who labor and are heavy laden, and I will give you rest. Take my yoke upon you, and learn from me: for I am gentle and lowly in heart: and you will find rest for your souls. For my yoke is easy and my burden light." (Mt 11: 28-30)
Jesus Christ also said: "Consider the lilies, how they grow; they neither toil nor spin; yet I tell you, even Solomon in all his glory was not arrayed like one of these.But if God so clothes the grass which is alive in the field today and tomorrow is thrown into the oven, how much more will he clothe you, O men of little faith! And do not seek what you are to eat and what you are to drink, nor be of anxious mind. For all the nations of the world seek these things; and your Father knows that you need them. Instead, seek his kingdom, and these things shall be yours as well. (Lk 12:27-31)
In his discussion with a young man, he also said: "Only God is good." (Luke 18:19)
Theological and philosophical basis of the doctrine
On the part of man
According to Christian philosophy, the basis of the doctrine that only God satisfies the human soul is that the faculties of man which makes him really human are the intellect and will. These two faculties, which distinguishes him from animals, are "open to the infinite."
This means that with his intellect or mind, man can always "know more" i.e. he can keep on receiving new information, new meaning without ever filling up. He can also "love more", i.e. he can always expand the quantity of the people and things he loves, and he can also improve the quality of that love. Thus only the Infinite God can satisfy the human spirit that is open to the infinite.
On the part of God
Christian theology says that God is I am that I am. He alone IS. He is Subsistent Being from whom all the other beings get their existence and their force. Thus compared to him the other beings are nothing. Compared to God who is All Goodness, his creatures as "no good." And in Metaphysics, we are told that Being = Goodness, and that "good" means "that which everything desires." Thus God, who is Goodness Itself and the source of all goodness, is the only one which can satisfy man's desires.
Peter Kreeft, a Christian philosopher who follows the steps of Thomas Aquinas, says that only God wins in the list of Candidates for the Greatest Good. He lists down other candidates which people seek: pleasure, power, money, honor, virtue, wisdom. And they all pale in comparison with God because they are temporary, limited, and many are means to an end and not the end itself. Peter Kreeft is a Catholic apologist for Christianity, professor at Boston College, and author of many books. ...
This is also based on the experience of people: materials things do not satisfy completely and people are easily satiated with them. Some management literature says:
- Salary is no longer the sole satisfier, nor the key to employee loyalty. Instead, loyalty is tied to the feelings workers get from their workplaces, and the values and ethics that are transmitted from the leadership. Just like Tom Cruise's character in the movie Jerry McGuire, employees are seeking deeper meaning and inspiration from their work, evaluating their companies' ethics and searching for their own. 
Testimonies of the saints
St. Cyprian is one of the Fathers of the Church. He is known for his defense against Nestorianism. The Church Fathers or Fathers of the Church are the early and influential theologians and writers in the Christian church, particularly those of the first five centuries of Christian history. ...
- To those who seek the kingdom of God and his righteousness, he has promised to give all else besides. Since everything indeed belongs to God, he who possesses God wants for nothing, if he himself is not found wanting before God. 
St. Augustine is the foremost Father of the Church. In modern language, he was considered a playboy and a cafeteria believer, choosing whatever faith suited him. These did not satisfy him thus he wrote one of his most famous words: The Church Fathers or Fathers of the Church are the early and influential theologians and writers in the Christian church, particularly those of the first five centuries of Christian history. ...
- You have made us, O Lord, for yourself, and our heart is restless until it rests in you. (Confessions of St. Augustine, 1)
- We all want to live happily; in the whole human race there is no one who does not assent to this proposition, even before it is fully articulated. How is it, then, that I seek you, Lord? Since in seeking you, my God, I seek a happy life, let me seek you so that my soul may live, for my body draws life from my soul and my soul draws life from you. 
St. Thomas Aquinas
Called the universal teacher of doctor, Thomas Aquinas is considered by many as one of the great geniuses of all times. He wrote the Summa Theologiae, a summary or compendium of theology.
- Eternal life is the perfect fulfillment of desire, because each of the blessed will have more than he desired or hoped for. In this life, no one can fulfill his desires, nor can any creature satisfy a man’s craving. God alone satisfies and infinitely surpasses man’s desires, which therefore can never rest except in God.
St. Teresa of Avila
St. Teresa of Avila is one of the few women Doctors of the Church.
- Let nothing trouble you
- Let nothing frighten you
- Everything passes
- God never changes
- Obtains all
- Whoever has God
- Wants for nothing
- God alone is enough. 
St. Josemaria is the founder of Opus Dei who preached about the universal call to holiness. Central Message of Saint JosemarÃa EscrivÃ¡, Founder of Opus Dei: Joy comes from knowing we are children of God. ...
Universal Call to Holiness and Apostolate is a teaching of the Roman Catholic Church that all people are called to be holy. ...
- After twenty centuries, we have to proclaim with complete conviction that the spirit of Christ has not lost its redemptive force, which alone can satisfy the desires of the human heart. Begin by feeding that truth into your own heart, which will be perpetually restless, as Saint Augustine wrote, until it rests entirely in God. 
- Once we recognise the insignificant and contingent nature of our earthly endeavours, the way is then open for true hope, a hope which upgrades all human work and turns it into a meeting point with God. ... Perhaps there is no greater tragedy for man than the sense of disillusionment he suffers when he has corrupted or falsified his hope, by placing it in something other than the one Love which satisfies without ever satiating. 
- 'Stay with us; it is towards evening, and it is far on in the day,' night is coming on. That's just like us. Always short on daring, perhaps because we are insincere, or because we feel embarrassed. Deep down, what we are really thinking is: 'Stay with us, because our souls are shrouded in darkness and You alone are the light. You alone can satisfy this longing that consumes us.' For 'we know full well which among all things fair and honourable is the best: to possess God for ever.' 
Catechism of the Catholic Church
The Catechism of the Catholic Church is the result of four centuries of scholarship and teaching after the Catechism of Trent of the 16th Century.
- The Beatitudes respond to the natural desire for happiness. This desire is of divine origin: God has placed it in the human heart in order to draw man to the One who alone can fulfill it. 
- The beatitude we are promised confronts us with decisive moral choices. It invites us to purify our hearts of bad instincts and to seek the love of God above all else. It teaches us that true happiness is not found in riches or well-being, in human fame or power, or in any human achievement - however beneficial it may be - such as science, technology, and art, or indeed in any creature, but in God alone, the source of every good and of all love.
Islam also refers to Allan (God) as AS-SAMAD or The Satisfier of all needs: "He is ever-present, knowing your needs before you do and satisfying them in the way they should be satisfied."