Why should we be civil?   Isn't 'every man for himself' the natural tendency that we were born with?   (observe toddlers in a group if you don't think so)

Even Capitalism is based on every person looking after their own interests.   

Have things changed?   Have we moved from an age of civility into an age of incivility?   

It depends on who and what you look at.   

What governs the average person's behaviour?   
   → parents
   → education
   → friends (and enemies)
   → experiences
   → decisions

Did a person have good parents, a good education, good friends, good experiences and make good decisions?   

It is a fact that not all of the influences on people are good, especially today in an age of moral relativism.   

And even the definition of 'good' has been tampered with of late.   

Back to civility...   

Unless a person subscribes to a traditional value system, civility is not even their concern.   

Traditional values were based on religious principles.   In Western Civilization that religion is Christianity.   

As the west has lost touch with its roots In Christ Jesus, the associated traditional values have been replaced by more pagan, hedonistic values.   

Accordingly, civility is no longer a priority or even expected.   (note how often people give each other the finger)

So, there was an Age Of Civility.   Not everyone was civil but society at large was civil.   And that is why we call it 'western civil ization'.   

The spread of Christianity throughout Europe, North Africa, western Asia and then into the western hemisphere was the foundation for man being civil to man.   

That civility brought cooperation leading to advances in science and ultimately the formation of the USA based on freedom and self governance.   

When a person is in bondage it is difficult for them to be civil.   As Christianity has been left behind by the modern philosophers, educators and politicians we see an increase in incivility.   

We can all see the destruction being wreaked on society because of identity politics emphasizing our differences rather than our commonality.   

The Bible teaches us that while Satan is the author of confusion, a killer, stealer and a destroyer, it also teaches us
   → that we are one in the Lord Jesus Christ,
   → that we are accepted by Him and
   → that we are empowered by His Holy Spirit to be in fellowship with fellow believers.   

So, Civility is not natural.   
Civility is supernatural.   
Civility is a work of the Holy Spirit in us.