Salt appears in the following:
Matthew 5:13 Ye are the salt of the earth: but if the salt have lost his savour, wherewith shall it be salted? it is thenceforth good for nothing, but to be cast out, and to be trodden under foot of men.
Mark 9:49 For every one shall be salted with fire, and every sacrifice shall be salted with salt.
Mark 9:50 Salt is good: but if the salt have lost his saltness, wherewith will ye season it? Have salt in yourselves, and have peace one with another.
Luke 14:34 Salt is good: but if the salt have lost his savour, wherewith shall it be seasoned?
Colossians 4:6 Let your speech be alway with grace, seasoned with salt, that ye may know how ye ought to answer every man.
James 3:12 Can the fig tree, my brethren, bear olive berries? either a vine, figs? so can no fountain both yield salt water and fresh.
Salt is a preservative which makes bland food palatable.
It thus represents those who live according to God’s commandments whose speech and actions are full of grace and truth.
They understand and believe the gospel and obey it, living their lives according to the precepts of Jesus Christ.
1 Peter 3:15 But sanctify the Lord God in your hearts: and be ready always to give an answer to every man that asketh you a reason of the hope that is in you with meekness and fear:
Those who do this fulfil the Law inasmuch as they love their neighbour as themselves.
Romans 13:8 Owe no man any thing, but to love one another; for he that loveth another hath fulfilled the law.
Light is used symbolically for the word of God.
The preaching of the word of God causes light to shine in a dark place.
In this sense Jesus is the light of the world and those who believe and teach the gospel are also lights.
Matthew 5:14 Ye are the light of the world. A city that is set on an hill cannot be hid. 15 Neither do men light a candle, and put it under a bushel, but on a candlestick; and it giveth light unto all that are in the house. 16 Let your light so shine before men, that they may see your good works, and glorify your Father which is in heaven.
To walk in the light is to live by the commandments of Jesus Christ.
1 John 1:7 But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin.
1 John 2:9 He that saith he is in the light, and hateth his brother, is in darkness even until now. 10 He that loveth his brother abideth in the light, and there is none occasion of stumbling in him.
Ephesians 5:8 For ye were sometimes darkness, but now are ye light in the Lord: walk as children of light:
Jesus fulfilled the Law of Moses and took it out of the way.
Those who believe the gospel and are baptised into Christ, are not under the Law of Moses, they are under the Law of Christ.
Galatians 2:16 Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.
Galatians 2:21 I do not frustrate the grace of God: for if righteousness come by the law, then Christ is dead in vain.
Galatians 3:13 Christ hath redeemed us from the curse of the law, being made a curse for us: for it is written, Cursed is every one that hangeth on a tree:
I hope this helps.