Sigh. It is so tiring to hear, once again, the "If Christians really believed the Bible, they would kill all gay people" line. It is simply not true that an accurate following of the Bible would nessesitate killing of homosexuals.
The Bible, as with any ancient text, needs to be read alongside other texts of the time, in the context of the culture of the time. You need to read the whole text. You need to know who it was writen by, who it was writen to, and for what purpose. What else was going on at the time it was writen? Who was the King? What wars were in progress? What were the laws and traditions of the time etc etc.
Historians, Christian and otherwise, always read texts in this way and interpret them acordingly. To quote a random verse is not even remotely helpful if you genuinely want to understand and interpret the Bible, although it is obvious that is not the intended outcome here anyway.
Old Testament Law (Including Leviticus) did legislate death as a punishment for some sins. Braodly speaking, these were laws which gave the Israelites a understanding of God's standards and His nature, and set Israel apart from the other nations in the region. Israel was to follow God's laws to the letter in order to demonstrate their alliegence to their God and show their faith in Him. This was how they would be saved.
The New Testament is to be read 'differently'. This is a right, historical reading of the text, not a clever way for Christians to find loopholes. Jesus said "Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them." (Matt 15: 17). So God's standards for holiness in Old T law were fulfiled by Jesus' perfection in the NewT.
God's standards haven't changed (Jesus goes on to say "I tell you the truth, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished.), but the Old T system of sacrifices and punishments has changed in the light of Jesus' punishment on the cross being the Ultimate, Once For All Sacrifice.
So whilst the spirit of Old T law remains (and hence, the things clearly prohibited by the law - homosexuality being one of those things - remain contrary to God's law), New Testament Christians are not required by the Bible to exact punishment on homosexuals, or anyone else for that matter. Rather, Jesus clearly advocates by his teaching and actions that all people can turn to him and be reconciled with God, and that likewise His followers should show love and compassion to all people.
This does not mean Christians must approve of or condone all behaviour, but Christians are certainly wrong to be cruel, violent or hateful to any person of any creed, race, sexual orientation, colour, ability etc.
It is possible to disagree that the Bible is true, but still understand what causes Christians to state that homosexuality is wrong without having to also kill homosexuals as the logical conclusion of their faith. This is not hypocrisy and incnsistency within the Christian Faith, but rather a logical and legitimate reading of the Bible.
I'm not sure if its worth posting this really. So often its allowable to 'Christian Bash', and it all seems a bit pointless to try and help people understand the viewpoint of Christians when they so clearly do not wish to. Hopefully this might allow you to get on with your debate without the need to keep trotting out the "If Christians were anything but hyprcrits they would need to kill all gay people".
As you were.