The gospel of John tells us that eternal life begins in knowing our creator (Cf. Jn 17.3). Christianity lies in the words of Christ. Union with God is the aim of a life worth living. In knowing God we seek eternal life. However, this knowledge is not meant to puff up, convinced that it can know everything, including God (leading to the fall of Adam), and all the while remaining ignorant of the fact that our fall lies precisely in the decay of genuine knowledge. Adam's alienation from God, in his literal sense of choosing a life not in God, but in itself and by itself, Adam chose to "know God" which means to believe through that faith about which it is said that "even the demons believe and tremble". Adam ceased to know God, and his life ceased to be that meeting with God, that communion with him-communion with all of God's creation-all of which gives life as depicted in the book of Genesis. Humanity at it weakest point thirst a great thirst. The Psalmist proclaims, "my soul thirsts for the living God". The same God in which we thirst for, the God in which we seek union with, Adam chose to know God through his ego and selfishness.
Thanksgiving is the joy, fullness, presence, of knowledge of God. Knowledge as communion and knowledge as unity leads to thanksgiving. Knowing God transforms our life into thanksgiving, and thanksgiving transforms eternity into everlasting life. Fr. Alexander Schmemann sums it well when says that the Church above all is one big chorus of praise constantly called to give thanks:
It is Christ's knowledge of God that has been bestowed to humanity as a gift of thanksgiving. Christ has shattered the gates of hades and opened to us the gates of paradise. After Christ trampled down death by death, and when forgiveness of sins was sealed through Christ's act of death and resurrection, then there remained only praise, only thanksgiving. Thanksgiving, which unites us with God, thanksgiving which united all human beings. St. Paul reminds us that he became a Jew in order to win the Jew, he became a Greek in order to win a Greek. Thanksgiving does not need a barrier or ethnic background. Thanksgiving only requires on condition; love. Thanksgiving is granted to us as precisely a pure thanksgiving, like those prophets (Moses) who where in the presences of the face of God. When we realize we stand in the presence of God it is then that we will be able to genuinely start giving thanks for God's creation and offer it to all for the life of the world.