The Bible does not pick on certain sinners, while giving everyone else a pass. "All have sinned and fall short of the glory of God." (Romans 3:23) While the world attempts to figure out what causes bisexuality and homosexuality, Scripture explains where such desires originate. There will never be agreement on this issue between those who believe Scripture is the highest authority, and those who believe that man's educated guesses are the highest authority.
My thoughts here are based on the belief that Scripture is the highest authority. For 2000 years, Christianity has stood upon both the Old and New Testaments. And for 4000 years prior to Christ arriving on earth, God's people were guided by all of His rules for holy living. Throughout the history of Judaism and Christianity, bisexual behavior and homosexual behavior have been every bit as sinful as lying, stealing, adultery, and gluttony.
Those who rely upon educated guesses tend to seek scientific clues which they hope could point to a "gay gene." Those who rely upon Scripture point to something which exists deeper in man than his DNA. Since Scripture focuses upon man's spiritual life, the various sexual desires which man experiences are explained from God's vantage point. Scripture makes no effort to define man or his desires according to scientific research. Instead, God tells us directly in His Word what is inside of us, and what He expects of us.
For 6000 years now, God's design for marriage has involved a man and a woman. If you trace the timeline in the Old Testament, you will find that Adam and Eve lived roughly 4000 years before Christ was born in Bethlehem. Many people of course do not take the Bible literally. But for those of us who are convinced that the Old and New Testaments present literal history, we find many reasons to take God at His Word on this issue, and everything else He has graciously given us in Scripture.
Are certain people born bisexual? And are others born gay? Here is how Scripture addresses it. "Surely I have been a sinner from birth, sinful from the time my mother conceived me." (Psalm 51:5) Sin, like a person's DNA, is hereditary. We received sin from our parents. And they received it from their parents. And it can be traced all the way back to Adam and Eve.
But here again, the Bible does not pick on particular sinners. "All have sinned and fall short of the glory of God." (Romans 3:23) This is the obvious part of the equation. What isn't so easy to understand is why some people wrestle with desires which you or I never experience, and vice versa. The Bible does not elevate one group of sinners above another group. We are equally sinful before our Creator. And the Bible prescribes only one solution for sinners, regardless of desires, scientific research, orientation, background, family history, and personal tendencies. The only solution for sin is the cross of Jesus Christ.
Jesus died for people who struggle with lying; and people who struggle with adultery; and people who struggle with gossip; and people who struggle with being judgmental; and people who struggle with bisexuality; and people who struggle with greed; and people who struggle with homosexual desires; and people who struggle with pride. You see, Jesus died for all people. (see 2 Cor. 5:14,15)
While the world grapples with the idea of a gay gene, Scripture is light years ahead of that theory. At the end of the day, regardless of educated guesses, God's plan for marriage between a man and a woman is the only acceptable place for sex.
Since we live in a sexually-charged society, many today are in need of God's forgiveness for sexual sins. But regardless of whether or not you have "kept the marriage bed pure," (Hebrews 13:4) you are in need of the cross. Your soul needs the living water of the Holy Spirit, who enters a person the moment you repent of sin and trust Christ for the forgiveness of sins. Once that happens, your body becomes a temple of the Holy Spirit. (see 1 Cor. 6:19) And the Lord is greatly concerned about what happens in His temple.
When a believer engages in sexual sin, it is essentially like committing that sexual act in the building where Christians gather to worship. As a Christian, you are in "church" 24/7. Your body and the bodies of other believers make up God's temple today. So even when the church building sits empty, God remains in His temple inside of you and all Christians. You have a personal relationship with the Lord. He loves you dearly, and He has a plan for your life and your sexuality.
Jesus said, "For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false testimony, slander." (Matthew 15:19) Instead of pointing to DNA or science or genes, Jesus referred to the sinful desires which flow out of the heart of man. Apart from Scripture, we would not have this knowledge which transcends educated guesses. God's description is completely accurate, regardless of man's opinions, research, DNA, and orientation.
Bisexual and homosexual behavior are two of the many sins which come from the "sinful nature" of man. (see Galatians 5:19-21) You see, we were all born with a predisposition to sin. The New Testament explains that man's sinful nature is a part of his existence throughout his life on earth. (see Romans 7:21-25) But that doesn't mean we as believers have to be dominated by sin. Not by a long shot. There is freedom in Jesus to reserve our mind and our body for God's holy purposes. (see Romans 6:20-23)
There are no easy answers for the one who feels that he or she will never desire a romantic relationship with a person of the opposite sex. While there are certainly people who have chosen to transition out of bisexual behavior and homosexual behavior, there are many others who claim that such a transition is impossible. Again, much of this discrepancy is connected to whether a person views Scripture as the highest authority, or educated guesses as the highest authority.
Those who believe firmly in Scripture have plenty of reasons to believe that Jews and Christians for 6000 years have properly understood God's design for marriage. That's not to say there haven't been plenty of Jews and Christians over the centuries who have committed sexual sin. But it is to say that God's boundary line for marriage and sex is immovable, and it hasn't shifted in spite of the sexual upheaval within our postmodern culture.
God created you to make choices. And one of your biggest decisions in life will be how you choose to view Scripture in the grand scheme of things. You may choose to take the Bible with a grain of salt, or you may accept it as God's love letter to His people. Whichever view you choose, it will do nothing to change the power, authority and inerrancy of God's Word. But your decision will determine whether or not you begin to find relief and deliverance in the words of Scripture.
If you have encountered prejudice or even hatred around the issue of your sexuality, please be assured that Christ is not the source of such mean-spirited abuse. You see, God has always condemned the sin in man, while at the same time loving the sinner. If He didn't, then He would never have sent His only Son to suffer and die on a cross for our sins. That is the message of Scripture. And you are free to accept it with all of its promises for those who follow Christ; or to reject it with all of its warnings to those who choose to do their own thing.
Ultimately, it won't matter how many theories are proposed concerning a gay gene. The Bible explained our "spiritual DNA" long before scientists started trying to figure out human sexuality. No one knows us better than the One who created us.
The Lord wants to bless you with wisdom, discernment, repentance, and faith. If you experience the miracle of the new birth by receiving Jesus as your Savior, you will find that a personal union with God goes deeper than a sexual union with another human being. At the end of the day, Scripture not only transcends the gay gene hypothesis, but it also transcends the entire gamut of sinful desires which human beings experience here on earth.
So who or what is Lord of your life? Your sexual desires, or the One who created you to live for Him? Sexual desires don't justify sexual sin, regardless of the research behind it. And educated guesses will never catch up with divine revelation, no matter how much we try to convince ourselves otherwise.