Why can't people live together nicely?

-Hagar the Horrible-
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Colossians 2:8
"See to it that no one takes you captive through philosophy 
and empty deception, according to the tradition of men, 
according to the elementary principles of the world, 
rather than according to Christ."

Matthew 5:43-48
"You have heard that it was said, 
‘You shall love your neighbor and hate your enemy.’
 But I say to you, love your enemies 
and pray for those who persecute you, 
so that you may be sons of your Father who is in heaven; 
for He causes His sun to rise on the evil and the good, 
and sends rain on the righteous and the unrighteous. 
For if you love those who love you, 
what reward do you have? 
Do not even the tax collectors do the same? 
If you greet only your brothers, 
what more are you doing than others? 
Do not even the Gentiles do the same?
Therefore you are to be perfect, 
as your heavenly Father is perfect."

Isaiah 1:2-20
“Listen, O heavens, and hear, O earth;
For the Lord speaks,
“Sons I have reared and brought up,
But they have revolted against Me…

…“Wash yourselves, make yourselves clean;

Remove the evil of your deeds from My sight.

Cease to do evil,

Learn to do good; 
Seek justice,

Reprove the ruthless,
Defend the orphan,
Plead for the widow.

“Come now, and let us reason together,
”
Says the Lord,
“Though your sins are as scarlet,

They will be as white as snow;

Though they are red like crimson,

They will be like wool.

“If you consent and obey,
You will eat the best of the land;

“But if you refuse and rebel,

You will be devoured by the sword.
”
Truly, the mouth of the Lord has spoken.”
                         
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