Imagine if we all talked like Paul. Imagine if instead of 'Hey, whats up?' we said 'Grace and peace to you from God our Father and the Lord Jesus Christ.' Paul was a powerful man of God, and he spoke like it.
In these last days we are living in, speech is primarily negative. We spend a lot of time making fun of each other, and the Bible says this is how we 'grieve the Holy Spirit of God'. A common slang that is supposed to mean "You are a funny guy" is instead verbalized as "You stupid!" We look for ways to cut each other down, make jokes about each other, and each of these lead to the narrative that Satan wants us to believe.
See Satan needs to take our power from us, he needs us to view ourselves as stupid, helpless, without spiritual power or conviction, and sinful. The more that he can use speech to make us feel this way, the more he hamstrings us and our ability to wage spiritual warfare.
But how does Paul say to talk about each other?
Eph 4:29 Do not let any unwholesome talk come out of your mouths, but only what is helpful for building others up according to their needs, that it may benefit those who listen. 30 And do not grieve the Holy Spirit of God, with whom you were sealed for the day of redemption. 31 Get rid of all bitterness, rage and anger, brawling and slander, along with every form of malice. 32 Be kind and compassionate to one another, forgiving each other, just as in Christ God forgave you.