A Oneness Created by a Giving of One's Self

Šĕmaʿ Yisĕrāʾel Ădōnāy Ĕlōhênû Ădōnāy eḥād.  Hear, O Israel: the LORD our God, the LORD is one (Deuteronomy 6:4). The One, the Holy One, the object of this sacred text is the Creator of the entire  universe according to the story in Genesis.  When it  says that God made us in his image and likeness (Genesis 1:27) we had a share in that attribute, that oneness with God that was paradise.  It was fractured by sinfulness  only to be regained in that new covenant of  Jesus, the Christ.  This covenant is a consecrated, physical, "bodily" covenant.   Christ says, Take and eat,  this is my body, which will be given up for you and for all that sins might be forgiven. Do this in memory of me.  In receiving the body of Jesus into their bodies Christians pledge to give their bodies in chastity, poverty and obedience to the Church's spouse who is one with his Father.  This is the oneness spoken of in the Shema Israel.  We call the Church  "catholic" which denotes the universal oneness of God in the requited love of His kingdom within and among us. 
Deuteronomy continues:

	5 And thou shalt love the LORD thy God with all thy heart, and with all thy soul, and with all thy might.
	6 And these words, which I command thee this day, shall be upon thy heart;
	7 and thou shalt teach them diligently unto thy children,  and shalt talk of them when thou sittest in thy house, and when thou walkest by the way,  and when thou liest down, and when thou risest up.
	8 And thou shalt bind them for a sign upon thy hand, and they shall be for frontlets between thine eyes.
	9 And thou shalt write them upon the door-posts of thy house, and upon thy gates. Because the Church isn't just theoretically wed to her spouse, but  bodily wed, she doesn't change her teaching on sex or divorce or the nature of marriage itself.  They are integral to her  being who she is.  We each have the particular bodies that we have in order to fulfill a vocation God has for each of us. We were given physical bodies with a spiritual purpose, called by our Creator to make visible, to "incarnate" our love for Him  in our daily lives.  We live a covenant with God, whether single or married, which is the essence of her teaching on chastity.  When the pagan and secular world press the Church to change its teaching on these matters, she holds steadfast because to do otherwise would be to deny her very essence.   Some of those who press for change are very learned and sincere people.  Jesus thanked his Father for hiding these things from the wise and learned and revealing them to little children (Matthew 11:25).