"Survival of the fittest" has nothing to do with individuals, it is an evolutionary concept concerning species and sub-groups and their fitness in the environment they live in.
Also, if I'm a born-again Christian, forgetting conscience, there is nothing to stop you from killing or stealing either since you are already guaranteed your place in heaven.
Anyway, most people can't afford the protection needed to prevent friends and relatives of the victims of their crimes from coming after them and exacting revenge. Forgetting conscience, there are still plenty of reasons obey society's laws. Anyone with half a brain knows it's beneficial to them to live in a stable, law-abiding society rather than a place where anarchy reigns supreme.
What you miss here is the core of the faith, which is a relationship with God. By doing wrong you damage the most important relationship in your life, bar none.
Luke 6:
Love for Enemies
27"But I tell you who hear me: Love your enemies, do good to those who hate you, 28bless those who curse you, pray for those who mistreat you. 29If someone strikes you on one cheek, turn to him the other also. If someone takes your cloak, do not stop him from taking your tunic. 30Give to everyone who asks you, and if anyone takes what belongs to you, do not demand it back. 31Do to others as you would have them do to you.
32"If you love those who love you, what credit is that to you? Even 'sinners' love those who love them. 33And if you do good to those who are good to you, what credit is that to you? Even 'sinners' do that. 34And if you lend to those from whom you expect repayment, what credit is that to you? Even 'sinners' lend to 'sinners,' expecting to be repaid in full. 35But love your enemies, do good to them, and lend to them without expecting to get anything back. Then your reward will be great, and you will be sons of the Most High, because he is kind to the ungrateful and wicked. 36Be merciful, just as your Father is merciful.
Judging Others
37"Do not judge, and you will not be judged. Do not condemn, and you will not be condemned. Forgive, and you will be forgiven. 38Give, and it will be given to you. A good measure, pressed down, shaken together and running over, will be poured into your lap. For with the measure you use, it will be measured to you." 39He also told them this parable: "Can a blind man lead a blind man? Will they not both fall into a pit? 40A student is not above his teacher, but everyone who is fully trained will be like his teacher.
41"Why do you look at the speck of sawdust in your brother's eye and pay no attention to the plank in your own eye? 42How can you say to your brother, 'Brother, let me take the speck out of your eye,' when you yourself fail to see the plank in your own eye? You hypocrite, first take the plank out of your eye, and then you will see clearly to remove the speck from your brother's eye.
A Tree and Its Fruit
43"No good tree bears bad fruit, nor does a bad tree bear good fruit. 44Each tree is recognized by its own fruit. People do not pick figs from thornbushes, or grapes from briers. 45The good man brings good things out of the good stored up in his heart, and the evil man brings evil things out of the evil stored up in his heart. For out of the overflow of his heart his mouth speaks. The Wise and Foolish Builders
46"Why do you call me, 'Lord, Lord,' and do not do what I say? 47I will show you what he is like who comes to me and hears my words and puts them into practice. 48He is like a man building a house, who dug down deep and laid the foundation on rock. When a flood came, the torrent struck that house but could not shake it, because it was well built. 49But the one who hears my words and does not put them into practice is like a man who built a house on the ground without a foundation. The moment the torrent struck that house, it collapsed and its destruction was complete."
What a lot of thinkers that have never believed miss is that salvation is not the only reason to be a Christian. To act as a Christian is to act with God, which is, in and of itself, joy. Sin is and of itself, destructive. Most are just too clouded in their thinking to see it.
Get your evolution right. Things evolve supposedly because more fit individuals pass on more of their genes.
Also, if I'm a born-again Christian, forgetting conscience, there is nothing to stop you from killing or stealing either since you are already guaranteed your place in heaven.
Bark up another tree with that silliness. I'm Catholic and believe in the ability to fail as a Christian. Salvation is not a wicket to hit once, its a life long journey. The Christian would not kill you because they love God. If they do not love God, then they are not a Christian. Yet many non-Christians who felt drawn to God will act with morality, because they have not yet hardened their hearts against him.
Anyway, most people can't afford the protection needed to prevent friends and relatives of the victims of their crimes from coming after them and exacting revenge. Forgetting conscience, there are still plenty of reasons obey society's laws. Anyone with half a brain knows it's beneficial to them to live in a stable, law-abiding society rather than a place where anarchy reigns supreme.
History does not support your assertion. Try Rwanda or the streets of LA.
Your "logical" idea that because stability and morality do provide a safer society, that they are natural is as absurd as the Utopian dreams of socialists. By your logic the Tragedy of the Commons would never exist, as it is in everyone's interest to put a little back in for the common good. The truth is that human nature does not support your notion that Christian values are "just natural".
But as I said, I'm flattered that even an atheist can see the superiority of such principles.