For married people, putting God first is both a blessing and a paradox. On the one hand it is God who gives us everything, on the other hand marriage is between two not three.
The human basis of marriage is the friendship which a man and a woman share; it is a unique kind of friendship because it involves the gift of one's life. So where does God fit into this? None of us have ever met two spouses who share their life with a third mysterious person!
Christian spouses mediate their own friendship with Christ to one another. A Christian man and a Christian woman have already entered into a friendship with Christ - it is this same friendship which they share with their spouse in marriage. Becoming one flesh for Christians means becoming one heart - a new heart. Indeed, this is the source and the goal of the spirituality of Christian marriage.
Speaking to the young people of Rome last April, Benedict XVI said:
"the Lord implants this new heart in us at Baptism, through faith. It is not a physical transplant, but perhaps we can make this comparison. After a transplant, the organism needs treatment, requires the necessary medicines to be able to live with the new heart, so that it becomes ones own heart and not the heart of another."
Such a process has happened with all of us who are baptised, and we are aware how God has "treated" us since then - in our renewed conversions, our awakenings, our prayer and the formation which we have received. In such a way have we progressed in friendship with Christ. For those who enter into the married vocation their hearts have already been formed for a life which is based on mediating my friendship with Christ with another person. This is how the Holy Father put it:
The Holy Father is here addressing the new evangelisation of marriage and the family: it is the work of God, a work which we must attune our selves to. Our spiritual formation is essential, a formation which begins for young people, those preparing for marriage and for spouses by letting Christ take us by the hand and by growing in friendship with him. He alone has the key to the human heart."Thus, by living in communion with Christ, with his Church, the new heart becomes "our own heart" and makes marriage possible. The exclusive love between a man and a woman, their life as a couple planned by the Creator, becomes possible, even if the atmosphere of our world makes it difficult to the point that it appears impossible. The Lord gives [to married people] a new heart and we must live with this new heart, using the appropriate therapies to ensure that it is really "our own". In this way we live with all that the Creator has given us and this creates a truly happy life."