John 15:19 – If ye were of the world, the world would love his own; but because ye are not of the world, but I have chosen you out of the world, therefore the world hateth you.
Romans 12:2 – And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God.
How I see that is, we are not supposed to act like the world. The world will swear and commit sinful acts, but we are to be pure and be good witnesses. People should be able to tell that we love God by the way that we act. Of course, everyone makes mistakes and no one is perfect but we can’t use that as an excuse to do something wrong. If I get upset with my best friend, I’m not going to slap her and then tell her two seconds later that no one is perfect! If you love God, than you should want to please Him and do as He says.
The Bible is clear on this topic;
Colossians 3:8 – But now you must put them all away: anger, wrath, malice, slander, and obscene talk from your mouth.
Matthew 15:10-11 – And he called the people to him and said to them, “Hear and understand: it is not what goes into the mouth that defiles a person, but what comes out of the mouth; this defiles a person.”
James 3:6-8 – From the same mouth come blessing and cursing. My brothers, these things ought not to be so.
Ephesians 5:4 – Let there be no filthiness nor foolish talk nor crude joking, which are out of place, but instead let there be thanksgiving.
Psalms 19:14 – Let the words of my mouth and the meditation of my heart be acceptable in your sight, O Lord, my rock and my redeemer.