So God created man in his own image, in the image of God he created him; male and female he created them.
(Genesis 1:27) ESV 

And God blessed them. And God said to them, “Be fruitful and multiply and fill the earth and subdue it 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.”
(Genesis 1:28) ESV 

Then the Lord God said, “It is not good that the man should be alone; I will make him a helper fit for him.” Now out of the ground the Lord God had formed every beast of the field and every bird of the heavens and brought them to the man to see what he would call them. And whatever the man called every living creature, that was its name. The man gave names to all livestock and to the birds of the heavens and to every beast of the field. But for Adam there was not found a helper fit for him. So the Lord God caused a deep sleep to fall upon the man, and while he slept took one of his ribs and closed up its place with flesh. And the rib that the Lord God had taken from the man he made into a woman and brought her to the man. ...
(Genesis 2:18-25) ESV 

Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh.
(Genesis 2:24) ESV 

  But I say to you that everyone who looks at a woman with lustful intent has already committed adultery with her in his heart.
(Matthew 5:28) ESV 

He answered, “Have you not read that he who created them from the beginning made them male and female,
(Matthew 19:4) ESV 

And I say to you: whoever divorces his wife, except for sexual immorality, and marries another, commits adultery.”
(Matthew 19:9) ESV 

But from the beginning of creation, ‘God made them male and female.’
(Mark 10:6) ESV 

For this reason God gave them up to dishonorable passions. For their women exchanged natural relations for those that are contrary to nature; and the men likewise gave up natural relations with women and were consumed with passion for one another, men committing shameless acts with men and receiving in themselves the due penalty for their error.
(Romans 1:26,27) ESV 

Or do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived: neither the sexually immoral, nor idolaters, nor adulterers, nor men who practice homosexuality, nor thieves, nor the greedy, nor drunkards, nor revilers, nor swindlers will inherit the kingdom of God.
(1 Corinthians 6:9,10) ESV 

Do not be unequally yoked with unbelievers. For what partnership has righteousness with lawlessness? Or what fellowship has light with darkness?
(2 Corinthians 6:14) ESV 

Now the works of the flesh are evident: sexual immorality, impurity, sensuality, idolatry, sorcery, enmity, strife, jealousy, fits of anger, rivalries, dissensions, divisions, envy, drunkenness, orgies, and things like these. I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God.
(Galatians 5:19-21) ESV 

But sexual immorality and all impurity or covetousness must not even be named among you, as is proper among saints.
(Ephesians 5:3) ESV 

Let marriage be held in honor among all, and let the marriage bed be undefiled, for God will judge the sexually immoral and adulterous.
(Hebrews 13:4) ESV