So... when people hold up signs quoting Leviticus re: homosexuality, they're wrong?
If you read and understand the Bible you will know that Leviticus is a historical account about ancient Israelites and their religious practice, which were held to the highest standard. In general, there is also a universal standard of right and wrong for all human beings. Most of which are written in our heart so that there is no excuse for one to claim that he/she doesn’t know what’s right and wrong. You may deny it but deep within you know the truth. The Bible doesn’t lay down the punishment for the gentiles except for one as laid down to Noah: God will demand an accounting for the life of another human being. That doesn’t mean there is no punishment for all other moral wrongs. Those are to be addressed by the court of justice set up by righteous people.
Leviticus and other OT scriptures such as Numbers and Deuteronomy were ancient account about ancient Israelites and their religious rites and laws that they and only they, had to follow. As such, the ancient Israelites were an entirely different matter. They were chosen and set aside by God to be His people as light to the world. As God’s ambassador, they were held to the highest standard. In addition, during Biblical times, God were with them. Since God is holy, the consequences of breaking God’s laws in His very presence were for the Israelites serious matter. Other tribes that were not Israelites didn’t have to observe the Hebrew rites and laws and thus were without the punishment unless it is a direct offence on God.
Since the ancient Israelites are no longer living in this days and age, and since the Temple in Jerusalem had been destroyed by the Romans 2000 years ago, the ten tribes of Israel, including the priest class, were dispersed and lost, the only remnant left is the tribe of Judah, which is the modern day Jews. As such, the Leviticus rituals and laws cannot be carried out.
Now, back to your question, those people holding up signs quoting Leviticus, is it wrong? It depends on what the sign was referring to. If it was referring to the fact that God viewed man lying with men as if a woman is wrong, then this moral view of God is also supported by Genesis where God said, man “is united to his wife, and they become one flesh”. Paul in the New Testament also covered such topic for the Christians.
Therefore, the punishment for homosexuality in Leviticus only applied to the ancient Israelites. For the gentiles and Christians who disobeyed, you can acknowledge your wrong and repent, or you can face judgment later after life. You may not believe it, but this is what the Christians believe. True Christians who tell you that homosexuality is wrong in the eyes of God do so without malice to save your soul.
In islam, as practiced in some islamic country, you will be hanged if stand accused of homosexual activity. Muslims still practice stoning women for adultery. Modern day Jews don't practice such detestable things, that's the difference.