Selfishness inside the church is a problem now and was a problem also in the 1st century. 
We are born selfish. That’s what it means to be a sinner. We were created for God – therefore God-centered – but sin made us become self-centered. And Christian discipleship is simply changing from self-centered to god-centered. 
Paul rebukes the Corinthians because some members brought a meal to church that was elaborate, while others had none. And they didn’t share! Bringing an elaborate meal was their way of advertising their wealth. (1 Corinthians 11) This is selfish! 
My experience in the church is that the hardest gap to bridge is the social status gap. It’s not the ethnic gap. It’s not even the age gap. It’s the economic gap. Most churches are made up of people similar in their social status. If you doubt this, think about your friends. Who do you hang out with most? Who do you vacation with? Aren’t they very close to you when it comes to social status?
If we are to be one – and we must be if we are in Christ – we must overcome this economic gap. We must associate with and love on those who are of different economic status. For example, if we are thinking of hosting an even that will cost money for the participants but some cannot make it due to financial difficulties, either we must not host it or pay their way so that they can make it. That is what love does.
Live for others. 
PH