You might want to provide some better evidence that there is a signficiant (or event insigificant) number of christian or jewish denominations which support killing of apostates.
You asked if there was any other religion that requires apostates to be killed, and doubted that Judaism or Christianity were among them. You were wrong.
Can you tell me which denominations exactly kill or advocate the killing of apostates?
I already gave you one. I believe the Holy Spirit Movement in Uganda is another. Many of the more extreme Calvinist and Presbyterian groups are Reconstructionist in their theology.
Are there any countries in which apostasy from Christianity or Judaism is considered to be a crime?
Not yet, though as I told you the group in the US is working very hard to make America one of those countries. Uganda might be next.
Not coincidentally, the two groups are rather friendly with each other.
Are there any Christian or Jewish theologians who advocate the killing of advocates?
Gary North, Gary DeMar, RJ Rushdoony, Greg Bahnsen...
How many Christian denominations teach that all the rules and regulations of the OT still apply to Christians today?
Fortunately very few. Most Christians don't follow that particular Biblical mandate. Even those who think the Bible is the literal and inerrant Word of God.
Those that
do follow it, however, have an undue political influence in America today.
How many apostates from Christianity or Judaism have been killed for being apostates?
Hard to tell, since the Lord's Resistance Army killed so many people for so many reasons.
...never thought I'd actually defend Christianity one day....
"Christianity" teaches the same thing that "Islam" teaches regarding apostasy. If you go by what their scriptures seem to directly command, both are equally "evil" in that regard. But, as your questions above seem to recognize, what matters isn't what "the scriptures teach", but what adherents actually
do. But there's nothing inherent in Islam that makes its command to slay apostates different from Christianity's command to do the same. There's simply a difference in the way many modern Muslims and many modern Christians interpret those commands (and even those ways differ from the ways Muslims and Christians
used to interpret them at various periods in their histories).
At the moment, for a variety of reasons mostly focusing on Christianity in the West going through a phase of development that Islam has not yet undergone as well as things still shaking out in the postcolonial era, there are more Muslims than Christians who advocate following the dictates regarding apostates that
both religions have. That needs to change (ideally via Islam going through an Enlightenment-type period, but there are other methods).
Saying "Islam is worse than Christianity because Islam says (or Islam's holy book teaches) that apostates should be killed while Christianity (or Christianity's holy book) doesn't!" isn't just flat-out
wrong, it's the wrong approach if your goal is to truly combat the problem of Islamic extremism and violence (especially if you want that nebulous "War on Islam but not on Muslims" thing everyone keeps bandying about).