Leviticus 18:22--And you must not lie down with a male the same as you lie down with a woman. It is a detestable thing.
Romans 1:26-27--That is why God gave them up to disgraceful sexual appetites, for both their females changed the natural use of themselves into one contrary to nature; 27) and likewise even the males left the natural use of the female and became violently inflamed in their lust toward one another, males with males, working what is obscene and receiving in themselves the full recompense, which was due for their error.
1st Corinthians 6:9, 10--What! Do YOU not know that unrighteous persons will not inherit God’s kingdom? Do not be misled. Neither fornicators, nor idolaters, nor adulterers, nor men kept for unnatural purposes, nor men who lie with men, 10) nor thieves, nor greedy persons, nor drunkards, nor revilers, nor extortioners will inherit God’s kingdom.
Up to you if you want to believe or not, but if you want to believe that the Bible is God's word, the anti-homosexuality scriptures are in there. There are more, but these were just the ones I knew off the top of my head.
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As to your second question...
1st Corinthians 6:9-11 (a continuation of the scripture from above)-- What! Do YOU not know that unrighteous persons will not inherit God’s kingdom? Do not be misled. Neither fornicators, nor idolaters, nor adulterers, nor men kept for unnatural purposes, nor men who lie with men, 10) nor thieves, nor greedy persons, nor drunkards, nor revilers, nor extortioners will inherit God’s kingdom. 11) And yet that is what some of YOU were. But YOU have been washed clean, but YOU have been sanctified, but YOU have been declared righteous in the name of our Lord Jesus Christ and with the spirit of our God.
Verse 11 says that if you choose to believe in the God of the Bible, repent of the action (feel regret over it), turn away from the action, and follow God's commands, you will be washed clean and the sin will not be held against you.