The light bulb is nothing without electricity. It was designed for illumination, but cannot, without energy, displace darkness. The light from a light bulb is a combination of three things: an incandescent filament that is part of an unbroken and uninterrupted electric circuit and of course, electricity. So, several simple things occur whenever the light bulb is ignited. The filaments within the incandescent bulb or the gases within the fluorescent tube must be intact. Obviously, the bulb must be properly connected to an electrical source (thus closing the circuit). The electrical switch must be turned on. Similarly, whenever Christians shine forth, there must be spiritual equivalents to the light bulb and spiritual equivalents to what makes the bulb works.
Our spiritual filaments are broken beyond repair. The Holy Spirit brings a new one. The Holy Spirit then also makes new electrical wiring and connections; our old circuitry is inadequate for His electricity and to make His filament work. Once the new equipment is in place and the Christian is properly connected to the spiritual energy source (God), he or she shines.
We can see it may take the Holy Spirit some time to set everything in place, at first the work is internal. In reality, He is limited by how fast we let Him work, and how much space we give Him. Once all is in place it should work continually, unless we find ways to interrupt it. Interruptions of the energy flow (for example, switches) can stop the electric flow, meaning that the hearing of faith and the believing of the Word is interrupted. The smallest cracks in the fluorescent tube or the tiniest breaks of an incandescent filament can destroy the bulb's capacity for lighting. So, can a break of the wiring. We should clarify that unlike our electrical sources, The Holy Spirit never has an outage. So, when our spiritual bulb ceases to shine light, it is not his fault it is ours.
In principle, this metaphor is very similar to the one Jesus used in John 15. We call it the Vine and the Branches. Christ told His disciples,
4 Abide in me, and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye, except ye abide in me.
5 I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing.
6 If a man abide not in me, he is cast forth as a branch, and is withered; and men gather them, and cast them into the fire, and they are burned.
7 If ye abide in me, and my words abide in you, ye shall ask what ye will, and it shall be done unto you.
8 Herein is my Father glorified, that ye bear much fruit; so shall ye be my disciples.
9 As the Father hath loved me, so have I loved you: continue ye in my love.
The branch that is connected to the vine (the trunk in the case of a tree), will feed off the sap that flows through vine or trunk. This will enable the branch to grow leaves, flowers and or fruits. This will be visible to all, and no one well be able to deny that the branch is connected to the vine or trunk, since "by the fruit you will know them" (Matthew 7:20). In this metaphor, if Christ is the Vine or trunk, then the Holy Spirit is the sap. The sap lubricates and feeds the branch. The sap gives the branch life; which is evident by the fruit.
What is the fruit? It is found in Galatians 5:22 – 23,
22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,
23 Meekness, temperance: against such there is no law.
In the same chapter Paul contrasted the fruit of the Spirit with the works of the flesh. This is what those who refuse to be part of the Holy Spirit circuitry or refuse to abide in Christ produce. Let us read,
19 Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness,
20 Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies,
21 Envyings, murders, drunkenness, revellings, and such like: of the which I tell you before, as I have also told you in time past, that they which do such things shall not inherit the kingdom of God.
If we were to see this passage in the light of Parable of the vine and branches these branches produce no fruit, and the works of the flesh are evident. The Father, who is the husbandman, cuts these branches away to make sure the vine or tree does not waste resources that the good branches could be using (John 15:1). These are those of which Christ says, "depart from me you workers of iniquity, I know you not" (Matthew 7: 23) these are professed believers Christ is speaking to. They attended church; they participated in all church activities and programs. They sang hymns, taught Sabbath School, returned tithes, even did evangelism. They were Sabbath School leaders, elders, deacons, etc. Christ says to them "I do not know you. Go away." They never got the point that only the daily indwelling of the Holy Spirit enables us to live a God-honoring life. Only the connection to the vine enables the Holy Spirit to produce fruit in them. Only the connection to the electric circuit enables the Spirit to shine the Light. How do we stay connected so the Holy Spirit can work through us? Through the hearing of faith (Galatians 3:1).