People who make a business of murdering babies are not good candidates for repentence ~ they might even say the words but they lie.
I agree with you there.
Nonetheless, we know that God can save the worst of sinners - thank God for that!
But I agree with your general premise - the vast majority of those who make it their business of murdering innocents aren't 'likely' candidates to repent. They have long ago rejected God and His Word, and hardened their hearts and ears to the call of the Holy Spirit. That said, every now and then God will pluck even one out of their midst and save them - perhaps just to show us His awesome power and mercy (and patience)...