When applying 1 Corinthians 5:11?

Rick, being a Christian is living a lifestyle that emulates the lifestyle of Jesus. Jesus associated with people with bad reputations meaning they had very low lifestyles, but these were not his associates. Put it another way--those he called friends were his followers, his twelve disciples and those he often saw, but not the publican, not the woman at the well, not those who would stone a woman caught in the act---these represent the ones he came to seek and to save. Now his associates are the type you and I are to have around us. They are our support group, they encourage(some time discourage) us, they help us believe in ourselves, our Church family can be the most powerful force in our life. Those who practice sins openly are to be avoided except for our witness, our assistance, and our charity--they are not counted among our circle of friends. We treat them as Jesus treated them for we too are here to seek and to save.

It is not a sin to eat with a crowd, In that crowd could be the next president, the next Billy Graham, the next bank robber, etc. They are not in your control so if you are invited to speak for instance at a ball held by the President--you do not know who else he may have invited--speak but speak what God would be pleased with you speaking. Now on the other hand, someone you know who lives like the scripture you used calls, invites you to a party which you know will be attended by other of that type---do not keep company with that type--do not go to the party. If pushed, give an explanation of why not in private, respect the others feelings always.

As Christians, we would not keep company with fornicators, adulterers, and other wrongdoers. Logically, then, we must not associate with such individuals by reading about them for sensual pleasure or by viewing them on television or in motion pictures. The heart is treacherous, can easily acquire a desire for bad things, and can be tempted to do them. (Jeremiah 17:9)

(1 Corinthians 15:33) Do not be misled. Bad associations spoil useful habits.

The very nature of Christianity demands that we show an interest in others—including those who do not share our beliefs. (Romans 10:13-15)

there is a clear difference between being friendly toward a person and being that one’s close companion.

the Bible’s words: “Whoever, therefore, wants to be a friend of the world is constituting himself an enemy of God.” (James 4:4)

When you read the Bible, you learn of many occasions when God loyally supported his friends. (Psalm 18:25; 27:10) You find out that his standards are always best and are for our lasting good. (Isaiah 48:17) Reading about God’s matchless qualities, such as his love and wisdom, inspires you to want to imitate him. (Ephesians 5:1) So, what you warn other Christians is about your faith/belief in the scriptures.You help another to keep clean from the daily temptations and entanglements that might contaminate a Christian while walking in this world.—Heb 10:22; Ga 6:1; Heb 12:13;

If your 'friends' accept your teachings they as well will love to learn what you have learned. On the contrary, they will continue to practice fornication, idolater, drunkard etc. therefore you should avoid them to not contaminate yourself from those wrong practices.

Jesus came to save His people from the sinful nature. We as Christians should tell everyone about Jesus and how Jesus came to save and cleanse us from our sins. Jesus said. I'm knocking at your door and if you open the door i will come in and eat with you and you with me. Just pray over your food all the time you eat.

1- yes of course

2- it's a sin but they just don't it (their fault though for not knowing the word of God on all things)

3- it would be the loving thing to do

Christ spent time with people who needed repentance. Only the sick need a doctor, and we all sin and are all sick.

if you knew what you were doing, it is a sin. If not, then no.