SPHERE OF INFLUENCE
There's another interesting definition I want to look at -- it relates to astrodynamics
A sphere of influence (SOI) in astrodynamics and astronomy is the spherical region around a celestial body where the primary gravitational influence on an orbiting object is that body. This is usually used to describe the areas in our solar system where planets dominate the orbits of surrounding objects (such as moons), despite the presence of the much more massive (but distant) Sun
Now, let's for just a moment consider the spiritual implications of this astrodynamic definition of "sphere of influence."
When we're conforming to the world, we might look at ourselves as moons. Despite the presence of a much more massive, much more powerful Son, a planet which is nearby influences or dominates our orbit, keeping us conforming to an orbit around that planet, rather than the significantly larger influence of the Son of God, our Lord and Savior Jesus Christ.
How does that look in real life? As followers of Christ, we know what the driving influence of our lives should be in this analogy -- the sun, (or Son) which is the things of God, as outlined in His Word, which tells us all that we need to know about faith and practice.
But the reality is, because of the way we sometimes choose to conduct our lives, there are things, like planets in this analogy, that are closer to us, and these things often have a greater influence on our thinking, and thus on our behavior, than the purity of devotion to Christ.