You are incorrect on that point.
On which point?
God does what is necessary.
Of course He does. But that doesn't change the fact that He does not currently speak to people directly.
I won't allow myself to abandon God for any other supposed authority's command to kill or anything else contrary to God.
How about what the Bible says? Is that contrary to God?
You shall not lie with a male as with a woman. It is an abomination.Nor shall you mate with any animal, to defile yourself with it. Nor shall any woman stand before an animal to mate with it. It is perversion. . . . For whoever commits any of these abominations, the persons who commit them
shall be cut off from among their people. - Leviticus 18:22-23,29
http://www.biblegateway.com/passage/?search=Leviticus18:22-23,29&version=NKJV
(reminder that "cut off" is a Hebrew idiom that means "to put to death")
If a man lies with a male as he lies with a woman, both of them have committed an abomination.
They shall surely be put to death. Their blood shall be upon them. - Leviticus 20:13
http://www.biblegateway.com/passage/?search=Leviticus20:13&version=NKJV
Therefore God also gave them up to uncleanness, in the lusts of their hearts, to dishonor their bodies among themselves,who exchanged the truth of God for the lie, and worshiped and served the creature rather than the Creator, who is blessed forever. Amen.For this reason God gave them up to vile passions. For even their women exchanged the natural use for what is against nature.Likewise also the men, leaving the natural use of the woman, burned in their lust for one another, men with men committing what is shameful, and receiving in themselves the penalty of their error which was due.And even as they did not like to retain God in their knowledge, God gave them over to a debased mind, to do those things which are not fitting;being filled with all unrighteousness, sexual immorality, wickedness, covetousness, maliciousness; full of envy, murder, strife, deceit, evil-mindedness; they are whisperers,backbiters, haters of God, violent, proud, boasters, inventors of evil things, disobedient to parents,undiscerning, untrustworthy, unloving, unforgiving, unmerciful;who, knowing the righteous judgment of God, that
those who practice such things are deserving of death, not only do the same but also approve of those who practice them. - Romans 1:24-32
http://www.biblegateway.com/passage/?search=Romans1:24-32&version=NKJV