It is in Genesis 1:21 was the sea creatures that God first commanded to be fruitful and multiply. Only on the next day after creating male and female, did God then say that we are to "subdue the earth and have dominion over the fish of the sea and over the birds of the heavens and over every living thing that moves on the earth." (Gen 1:27-29)
Thus, God's mandate to be fruitful and multiply to Adam and Eve (repeated later to Noah and his sons after the flood in Gen 9:1-3) is chiefly a practical command to populate the earth. But this kind of population is for two purposes. Firstly it is to be God's caretaker over all of the rest of creation, ruling over it all and being responsible for it. Secondly, it is to testify to God's abundant blessing, for fruitfulness in child-bearing is a sign of God's blessing and favour to mankind. (1 Chron 26:5) Thus this oft quoted phrase is not God's basis for marriage.
That is found in Genesis 2:24 - Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh.
To whom can we be more firmly bound in blood and flesh, than our fathers that begat us and the mothers that bore us? Yet the son must forsake them, to be joined to his wife, and the daughter must forget them, to cleave to her husband. The purpose of uniting in one flesh, is to reflect the mysterious union of the three-in-one God. And sex is the most intimate of this act of uniting as the Father, Son and Spirit are united. Apart from procreation, sex is a delightful act because husband and wife are engaged in the pleasure reflecting the Trinity in an act of love. It is God-glorifying in the context of marriage. Such pleasure is not the self-seeking kind we are so greatly enamoured of and use to justify our usage of implements and "toys", which are principally made for carnal delight and self-pleasure. The pleasure of sex in a sanctified marriage is a more glorious, selfless kind.
So, dear brothers and sisters, you have no obligation whatsoever to do what your sinful nature urges you to do. For if you keep on following it, you will perish. But if through the power of the Holy Spirit you turn from it and its evil deeds, you will live. For all who are led by the Spirit of God are children of God. So you should not be like cowering, fearful slaves. You should behave instead like God's very own children, adopted into his family - calling him "Father, dear Father." For his Holy Spirit speaks to us deep in our hearts and tells us that we are God's children. And since we are his children, we will share his treasures - for everything God gives to his Son, Christ, is ours, too. But if we are to share his glory, we must also share his suffering. || Romans 8:12-17 || NLT ||
Paul uses an incredibly intimate word for "Father" here. It is the term "Abba." The closest analogue we have is "Papa." The truth is, it is baby talk. The first stuttering syllables an infant utters are "pa, pa, Papa." It comes from the Latin "pater" or "father." The first words Jesus would have stammered would have been "ab, ab, Abba," from the Hebrew word for father, "av." In the upside down world of the Kingdom, only those who have found true maturity in the Spirit can speak to the Father like trusting toddlers.
Paul says it is the intimate name that the Holy Spirit enables us to speak to the Father, our Father. It is a name the Spirit deposits deep in our hearts. When we need it most, it is there, placed on our crying lips by the Spirit. (Gal. 4:6) It is a name Paul learned from Jesus, who in the garden, speaking more like a little boy than the tormented man He was said, "Abba, everything is possible for you..." (Mk. 14:36)
To experience God as Abba is to begin to know Him as Jesus knows Him. It represents a depth of intimacy that can only be had as a gift. You do not, cannot, earn it. You will not, ever, deserve it. It is the priceless treasure that you can only have for free. And the Spirit of God is waiting, longing to give it to you.