Salt and Light: The Two-fold Influence of Believers on the World
Matthew 5:13-16

Salt and Light. These two metaphors are used to summarize the two-fold influence that the subjects of the kingdom can have in this world. They are a summary of the effect of the beatitudes:
  1. Salt – the preserving influence of a righteous life. Up until the 20th century and the invention of refrigeration, salt was used as a preservative. it was useful in preserving the quality of stored food. in a similar way, the life and testimony (Col. 4:6) of believers in this world, ordering their lives consistent with God’s nature, is a moral preserver in the world (2 Thess. 2:7).
  2. Light – the incessant outflow of grace. while salt has its effect by staying true to what is inward, light has its effect by shining outward and illuminating. the character of God revealed in Christ is to be reflected to the world around. primarily through good works.
Note: There are two aspects of light (see notes on John 8 & 9). (1) it Exposes man’s condition – this is primary character of light, it “lightens” or illuminates every man (John 3:20-21, Eph. 5:13). (2) it is the knowledge of God’s character revealed in the person of the son – a knowledge that opens the spiritual eyes of a person to see the truth (II Cor. 4:6). our light will have this dual influence on this world.

Ye are the Salt of the Earth: Inward Righteousness (v.13)

 13 *Ye* are the salt of the earth; but if the salt have become insipid, wherewith shall it be salted? It is no longer fit for anything but to be cast out and to be trodden under foot by men. v.13 Salt speaks of the preserving influence of a righteous life on this world. salt is the only thing that cannot be salted, because it is the preservative principle itself. it is not just a substance… it is a quality! but if the quality of “saltiness” is gone, it cannot be replaced. the result is “gravel”. there is a danger that the salt could lose its savor (not a question of whether a saint can lose their salvation, but) that we can lose our righteous moral testimony. If this occurs, Christians become the subject of men’s ridicule. In Mark 9:50 we are told "have salt in yourselves". We must be determined to please the Lord no matter what the cost. Christ was the perfect example; "Bring me a new cruse, and put salt therein" (2 King 2:20).

Ye are the Light of the World: Outward Grace (vv.14-16)

14 *Ye* are the light of the world: a city situated on the top of a mountain cannot be hid. v.14 light speaks of the incessant outflow of grace. when our priorities are straight (a brightly lit city placed high above) this grace is something that cannot be hid. it is the unconscious fruit of the new nature.

15 Nor do men light a lamp and put it under the bushel, but upon the lamp-stand, and it shines for all who are in the house. v.15 but there is a need to order our lives to allow the light to shine. if we put our light under the bushel – perhaps our education, business, pleasure, etc. – we are hindering its shining. (Compare)

16 Let your light thus shine before men, so that they may see your upright works, and glorify your Father who is in the heavens. v.16let” – it is not something we have to try to do… but the clear away the obstacles and it will happen automatically. “good works” – these are things that must accompany the christian testimony. this out-shining of light will illuminate the world for what it is (Eph. 5:13)… a dark, cold, bitter place. it will lead souls to see the goodness of god (Rom. 2:4) and to turn in repentance to him, “glorifying our Father who is in heaven”.