In other days men had to go up to God. Now God has appeared unto us. He dwells in us and walks in us, not at stated seasons, but every hour of every day. How foolish, therefore, for men to talk about sacred seasons and holy days. There are no special sacred places and no special sacred days.
Fellowship has to do with sharing.
It can never be divorced from this idea. Through grace Jesus shared our lot. The Christian life is a shared response to God called forth by the gift of God of which we have been made partakers. We are made partakers of Christ through the gospel. Our obedience to the demands of the gospel, introduces us into that state or condition called fellowship with God.