Yes, I know Jesus told His disciples He would no longer call them servants, because they were His friends (Jn. 15:15), but let's look at the verse closely: "Henceforth I call you not servants; for the servant knoweth not what his lord doeth: but I have called you friends; for all things that I have heard of my Father I have made known unto you." Believers in Christ are His friends because He chooses to reveal God's truth to us. That does not mean, as His friend, I am equal to Him. It does not mean, as His friend, I no longer am expected to do His will. The Ephesian passage that best proves that salvation is a gift from God to all who will believe in Jesus (2:8-9), is followed by this verse: "For we are His workmanship, created in Christ Jesus unto good works, which God hath before ordained that we should walk in them" (2:10).
Yes, I know that the Apostle Paul wrote that believers are no longer servants of the Law, but are adopted children of God (Gal. 4:1-7). But notice in the passage, a child is treated as a servant until the Father determines he is mature enough to live on his own. Born again believers are somewhere on a continuum of spiritual maturity, from being "babes in Christ" (Mt. 11:25; 1 Cor. 3:1-2; 1 Pet. 2:2), to being "like Him" (which, according to 1 Jn. 3:2, only occurs following our looking upon Him face-to-face). God began the process (Jn. 3:3-8; Phil. 1:6), and He continues to mold and shape us into His Son's image and likeness (Rom. 8:28-30)!
The greatest joy a believer can have, is knowing he is in the will of Almighty God!