Friends, not servants

“I no longer call you servants, because a servant does not know his master’s business. Instead, I have called you friends, for everything that I learned from My Father I have made known to you.” John 15:15
God is very selective as to whom He chooses to call His friends. There was only one person in the Old Testament who was called a friend of God – Abraham (2 Chr. 20:7, James 2:23). Even Moses, while God “would speak to [him] face to face, as a man speaks with his friend” (Ex. 33:11), was called God’s servant [1]. We are very privileged to be counted as God’s friends.
Jesus tells us here that friendship with Him comes with revelation from the Lord. This was the case for Abraham; see Gen. 18:17.
The major difference between a servant and a friend is that a servant’s job is to obey (such as Moses, being given the Law). A friend is not an employee, but one to spend time with, one to share with, one to understand and be understood by you. Jesus taught His disciples many things about the Father, even though they didn’t understand it straight away. He showed them the things that would come to pass in the future – speaking often about His death and resurrection, and the Second Coming.
The revelation of God is ongoing in each of our lives, and will not be complete until we get to heaven. Paul says, “Now we see but a poor reflection as in a mirror; then we shall see face to face. Now I know in part; then I shall know fully, even as I am fully known” (1 Cor. 13:12). We can take comfort in hard times. If we were the servants of God, He could require us to do the dirty jobs just because they need to be done. But because we are His friends, everything that He brings us through is ultimately for our benefit and growth.

[1] Ex. 14:31, Num. 12:8, Deut. 34:5, Josh. 1:1, 1:13, 1:15, 8:31, 8:33, 9:24, 11:12, 11:15, 12:6, 13:8, 14:7, 18:7, 22:2, 22:4-5.