“Though this guy was probably the worst human being on earth, the only one that should be allowed to take his life is the Lord.”
Not true; if the government decides a person should die for crimes it is biblical.
War is biblical as well.
Biblical justification of war and capital punishment rest on the principle of legitimate rulers, even tyrants (Romans 13) can have legitimacy and revolt against them is justified (like war) only as a last resort and with proportionate means etc.
That’s not what happened here. This was vigilante justice and it violates the rule of law. Both anarchy and abortion are evil. Two wrongs don’t make a right.
The government should be the absolute last entity to decide on someone’s life, liberty, or pursuit of happiness.