There is an old adage in sports, and it is "Keep your eye on the ball!" This is the first fundamental in all of sports, because the game revolves around the ball, and each player has responsibilities relative to their position to the ball. So if a player loses track of the ball, he cannot and will not function properly. This seems relatively simple; but because it is simple, it easy to get sidetracked into putting your attention on all the other activities or movements that are going on around the ball so that the ball no longer has your attention.
There is a similar fundamental in the life of the church in that the life of the church revolves around Jesus Christ, and the minute any church takes its eyes off of Christ, removes its focus from Christ, and Christ ceases to be its priority, then it ceases to function properly even though it might be generating a lot of activity. If you read through the letters to the seven churches in Revelation, what you will see as a common thread among the churches that were chastised is that, in some fashion, they had taken their focus off of Christ and put it somewhere else.
This is what Paul warned the Corinthian church about in II Corinthians 10:3 "But I am afraid that as the serpent deceived Eve by his craftiness, your minds will be led astray from the simplicity and purity of devotion to Christ." This deception that takes a church's eyes off of Christ is a common, but effective tactic of the enemy; and he deceives us with many churchy, well meaning, feel good, even popular/missional du jour type of things; and it is so easy to be led astray by these things. Because of this, we must be vigilant and fight tenaciously to keep our eyes and our focus upon Jesus Christ and keep Him central to all that we are and do.
We must make sure that Christ is the center of our attention and the focus of our devotion. This is fundamental to all that we do as a church. So, just as good sports teams do, let us make sure that we are spending time focusing on the fundamentals, really The Fundamental, so that what we do as a church will be pleasing to the Lord, and our lampstand will not only remain in place, but its light will shine brightly.