The Christian Mission Statement is to know God and to make Him known. It starts by being in the closest possible fellowship with God. Fellowship in the style of Abraham and Moses.
To have fellowship with God in the style of Abraham (Genesis 18) or Moses (Exodus) is to live so obsessed by God that the abiding awareness of Him continuously pushes itself to the forefront of your life (Acts 17:28). As compared with simply feeling His presence occasionally in prayer or Sabbath worship, it is a level of intimacy in which you never even need to ask Him to show you His will. Where your common-sense decisions are actually His will for you. It is a level of intimacy where you know that if your decisions are wrong, He will produce a sense of restraint brought on by a check in your spirit. And that you will stop immediately. This, then, is fellowship.