What did Jesus reveal about the definition of marriage?
But from the beginning of creation, God made them male and female. For this reason a man shall leave his father and mother, and the two shall become one flesh; so they are no longer two, but one flesh. What therefore God has joined together, let no man separate. (Mark 10:6–9 NASB; cf. Matt 19:4–6)
What did Jesus proclaim about sex outside of marriage — fornication?
That which proceeds out of the man, that is what defiles the man. For from within, out of the heart of men, proceed the evil thoughts, fornications, thefts, murders, adulteries, deeds of coveting and wickedness, as well as deceit, sensuality, envy, slander, pride and foolishness. All these evil things proceed from within and defile the man. (Mark 7:20–23; cf. Matt 15:18–20)
According to these words, sex outside of marriage between one man and one woman is evil according to Jesus.
What is the conclusion?
(1) If Jesus said nothing about sex outside of marriage, then He neither defined marriage nor condemned extramarital sex.
(2) However, Jesus did define marriage and He did condemn extramarital sex (cf. Mark 7:20–23; 10:6–9).
(3) Therefore, Jesus did say something about sex outside of marriage.
What Should Humanity Conclude about Jesus?
Jesus said, “For whoever is ashamed of Me and My words, the Son of Man will be ashamed of him when He comes in His glory, and the glory of the Father and of the holy angels” (Luke 9:26).
“I am the way, and the truth, and the life; no one comes to the Father but through Me” (John 14:6).
“He who has My commandments and keeps them is the one who loves Me; and he who loves Me will be loved by My Father, and I will love him and will disclose Myself to him” (John 14:21).
“And if anyone hears My words and does not believe, I do not judge him; for I did not come to judge the world but to save the world. He who rejects Me, and does not receive My words, has that which judges him—the word that I have spoken will judge him in the last day” (John 12:47–48).
“For God so loved the world, that He gave His only begotten Son, that whoever believes in Him shall not perish, but have eternal life. For God did not send the Son into the world to judge the world, but that the world might be saved through Him. He who believes in Him is not judged; he who does not believe has been judged already, because he has not believed in the name of the only begotten Son of God. This is the judgment, that the Light has come into the world, and men loved the darkness rather than the Light, for their deeds were evil. For everyone who does evil hates the Light, and does not come to the Light for fear that his deeds will be exposed. But he who practices the truth comes to the Light, so that his deeds may be manifested as having been wrought in God” (John 3:16–21).