We understand your concern about the lack of courtesy and friendliness in the world today. You are not wrong in your observations, and we appreciate your desire to seek biblical guidance on this matter.
The Bible indeed teaches us to practice the Golden Rule with everyone, not just those in our inner circle. Jesus said, For all the law is fulfilled in one word, even in this: You shall love your neighbor as yourself. Galatians 5:14. This means we are to treat others with the same kindness, respect, and love that we would like to receive.
Moreover, we are called to be lights in the world, which includes being courteous and friendly to all. You are the light of the world. A city located on a hill can't be hidden. Neither do you light a lamp, and put it under a measuring basket, but on a stand; and it shines to all who are in the house. Even so, let your light shine before men; that they may see your good works, and glorify your Father who is in heaven. Matthew 5:14-16.
Regarding your second question, yes, this line of thinking can be a result of our fallen nature. The Bible tells us that our natural tendency is to serve ourselves and that we need the transforming power of the Holy Spirit to overcome this. For I know that in me, that is, in my flesh, dwells no good thing. For desire has conceived in me, bringing forth fruit of death. Romans 7:18.
As Christians, we are called to be different, to stand out, and to show the love of Christ to everyone. Be kind to one another, tenderhearted, forgiving each other, just as God also in Christ forgave you. Ephesians 4:32. Therefore, beloved, as you have obeyed, not only in my presence, but now much more in my absence, work out your own salvation with fear and trembling. For it is God who works in you both to will and to do for his good pleasure. Philippians 2:12-13.
Let us pray together:
Dear Heavenly Father,
We come before you today, lifting up this concern about the lack of courtesy and friendliness in the world. Help us, your children, to be beacons of light and love in a world that often chooses darkness and indifference. Fill our hearts with your love, so that we may extend it to everyone we meet, not just those in our inner circles. Help us to be transformers in society, reflecting the kindness and compassion of Jesus Christ in all our interactions. Give us the grace to overcome our fallen nature and to truly love our neighbors as ourselves. We ask this in the mighty name of Jesus Christ, our Lord and Savior. Amen.
We also would like to encourage you to continue to shine your light in this world, to stand up for what is right, and always be an ambassador for Jesus Christ with your words and actions.