Jesus was indeed a friend of sinners (Luke 7:34)… but he had fellowship with the disciples. Friendship and fellowship are not the same. You’ve got to know the difference between the two. Otherwise you’ll find yourself running around with the world, doing what they do, thinking like they think and seeking after what they seek.

Christians are the temple of God. If you see every believer as a stone that makes up the temple with the Head stone being Christ, then you can see how we “fit” well together. Each believer is like part of a body. A persons hand fits very well with an arm, but it will not “fit” together with the branch of a tree. A hand can hold on to that branch and they can dwell together for a time, but they are not part of the same body. The branch belongs to the tree and the hand belongs to a person. In the same way, a Christian can spend time with an unsaved man, but until that man is part of the body of Christ there can be no permanent fellowship. The whole person will feel pain if the hand is hurt, and the hand will tend to an injured leg by rubbing and holding it. The body cares for itself. However, the branch of that tree knows nothing of that body when it moves, hurts or thinks. An unsaved person will not feel what the Christian feels, see what the Christian sees, think like the Christian thinks, or labor for eternity as every believer must.

"For where two or three are gathered together in My name, there I am in their midst." - (Mat 18:20)

When you spend time with a fellow Christian, God is in the midst. You are not spending time with one other person but two; that person, and God. This is the difference between fellowship and ‘hanging out’. Fellowship means God is also there, participating… saying words through His children, stirring their hearts up to feel what He feels, to have the insight and wisdom that He has… and this happens when you are gathered together with others in His name.

“Do not be unequally yoked together with unbelievers; for what fellowship does righteousness have with lawlessness? And what partnership does light have with darkness? And what agreement does Christ have with Belial? Or what part does a believer have with an unbeliever?” (2 Cor 16:14-15)

Your closest friends should be Christians. Find these close friends and do not give them up easily. Meet regularly with them. Cherish them, for a good friend is a gift of God. These are people that you can have deep fellowship with. He or she can pray for you and plead with the Lord on your behalf, talk with you of spiritual things, give you godly advice, share your burdens, inspire you, rebuke you, help guide you back into truth, understand your trials and tribulations from an eternal perspective, and do not forget that they are working together with you toward a common goal - to live for Jesus and please God. You tell me if there are even a handful of other gifts greater than a person like this! This is deep Christian fellowship. You have to seek that. Join a church with godly people that have a zeal for the Lord - people that talk about God outside of Sundays. And lastly, be that same person to others - the type of person that another Christian can be encouraged and built up with.

“A child of God can no more grow in the Lord without Christian fellowship than a newborn child can grow without milk.” - Anonymous