Scripture teaches us:
Be Holy
2Co 6:11 O Corinthians! We have spoken openly to you, our heart is wide open.
2Co 6:12 You are not restricted by us, but you are restricted by your own affections.
2Co 6:13 Now in return for the same (I speak as to children), you also be open.
2Co 6:14 Do not be unequally yoked together with unbelievers. For what fellowship has righteousness with lawlessness? And what communion has light with darkness?
2Co 6:15 And what accord has Christ with Belial? Or what part has a believer with an unbeliever?
2Co 6:16 And what agreement has the temple of God with idols? For you are the temple of the living God. As God has said:
 
"I will dwell in them
And walk among them.
I will be their God,
And they shall be My people."
2Co 6:17 Therefore
 
"Come out from among them
And be separate, says the Lord.
Do not touch what is unclean,
And I will receive you."
2Co 6:18 "I will be a Father to you,
And you shall be My sons and daughters,
Says the LORD Almighty."
Eph 1:3 Blessed be the God and Father of our Lord Jesus Christ, who has blessed us with every spiritual blessing in the heavenly places in Christ,
Eph 1:4 just as He chose us in Him before the foundation of the world, that we should be holy and without blame before Him in love,
1Pe 1:13 Therefore gird up the loins of your mind, be sober, and rest your hope fully upon the grace that is to be brought to you at the revelation of Jesus Christ;
1Pe 1:14 as obedient children, not conforming yourselves to the former lusts, as in your ignorance;
1Pe 1:15 but as He who called you is holy, you also be holy in all your conduct,
1Pe 1:16 because it is written, "Be holy, for I am holy."
It seems to me there are a few stipulations as to who and what is holy or sacred. As Christians we are holy because God is holy and life is sacred as we consider all life that pleases God should be sacred.
I'm thinking that life which is devoid of God, has nothing but wickedness in their hearts and minds and purposefully and maliciously set out to destory other lives for selfish reasons simply because it brings them pleasure might not be all that holy or sacred.
Just to be clear...I am by no means saying anyone who does not know the Lord that automatically equates that life is not precious nor valuable nor dear to us nor...especially by God.