Hedonism is: Pursuit of or devotion to pleasure, especially to the pleasures of the senses.
The following is a summary of Christian Hedonism by John Piper. To get the full story you can read his book "Desiring God: Meditations of a Christian Hedonist."
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A Summary of Christian Hedonism in Five Statements
1. The longing to be happy is a universal human experience, and it is good, not sinful.
2. We should never try to deny or resist our longing to be happy, as though it were a bad impulse. Instead we should seek to intensify this longing and nourish it with whatever will provide the deepest and most enduring satisfaction.
3. The deepest and most enduring happiness is found only in God.
4. The happiness we find in God reaches its consummation when it expands to meet the needs of others in the manifold ways of love.
5. To the extent we try to abandon the pursuit of our own pleasure, we fail to honor God and love people. Or, to put it positively: the pursuit of pleasure is a necessary part of all worship and virtue.