God gave us guidelines on how to treat non-Christians (outsiders). When He is talking about salt and light, He is talking about the fruit of the Spirit that should always be flowing through us.
Jesus said we can tell who is a Christian/has a good heart and who has a bad heart by the words that come out of their mouths and by the fruit of the Spirit. You will not find these attributes in a non-Christian.
We should walk in Wisdom when we are among non-Christians. That means our actions and words out of our mouths are our witness to them. They will think you are a hypocrite if you use foul language (unseemly language, offensive language and cursing) or do mean things. They recognize unconditional love when they see it because they are not used to it.
We should have a good work ethic. If we are hired to do something, we should do it to the best of our ability and cheerfully. They will notice that. Al lead a lot of men to Jesus because of this.
We should obey the laws of the land and pay our taxes even if we disagree with it. We should never knowingly speed or break any other laws. Here in the USA we have the unique rights to speak out about what is wrong and through our peaceful assembly and votes to change the laws that are wrong. If the only way to change a law is through the court system then we should pursue that course; but not by breaking the law.
Some laws can be changed in Congress, Senate and by the President's signature. Those who serve us in those capacities can be voted out or in according to how they represent us and thereby get laws changed.
Other laws have to be changed by the Supreme Court in accordance with the Constitution.
Roe v Wade (abortion) came into effect through the court system and the only way to change that is through the court system (IE: sue someone for "the right to life" and take it all the way to the supreme court). We do have the right to life, liberty and the pursuit of happiness.
Homosexual marriage is another one you might not agree with. It can only be changed by the court system because it is legal from a Supreme Court decision.
Read Proverbs. It is the book of Wisdom and an excellent guide.
Mat 12:34-37 "Brood of vipers! How can you, being evil, speak good things? For out of the abundance of the heart the mouth speaks. "A good man out of the good treasure of his heart brings forth good things, and an evil man out of the evil treasure brings forth evil things. "But I say to you that for every idle word men may speak, they will give account of it in the day of judgment. "For by your words you will be justified, and by your words you will be condemned."
Mat 3:10 "And even now the ax is laid to the root of the trees. Therefore every tree which does not bear good fruit is cut down and thrown into the fire.
Mat 7:15-23 "Beware of false prophets, who come to you in sheep's clothing, but inwardly they are ravenous wolves. "You will know them by their fruits. Do men gather grapes from thornbushes or figs from thistles? "Even so, every good tree bears good fruit, but a bad tree bears bad fruit. "A good tree cannot bear bad fruit, nor can a bad tree bear good fruit. "Every tree that does not bear good fruit is cut down and thrown into the fire. "Therefore by their fruits you will know them. "Not everyone who says to Me, 'Lord, Lord,' shall enter the kingdom of heaven, but he who does the will of My Father in heaven. "Many will say to Me in that day, 'Lord, Lord, have we not prophesied in Your name, cast out demons in Your name, and done many wonders in Your name?' "And then I will declare to them, 'I never knew you; depart from Me, you who practice lawlessness!'
Gal 5:22-26 But the fruit of the Spirit is love, joy, peace, longsuffering, kindness, goodness, faithfulness, gentleness, self-control. Against such there is no law And those who are Christ's have crucified the flesh with its passions and desires. If we live in the Spirit, let us also walk in the Spirit. Let us not become conceited, provoking one another, envying one another.
Eph 5:8 For you were once darkness, but now you are light in the Lord. Walk as children of light (for the fruit of the Spirit is in all goodness, righteousness, and truth), finding out what is acceptable to the Lord. And have no fellowship with the unfruitful works of darkness, but rather expose them.
Gal 5:19-21 Now the works of the flesh are evident, which are: adultery, fornication, uncleanness, lewdness, idolatry, sorcery, hatred, contentions, jealousies, outbursts of wrath, selfish ambitions, dissensions, heresies, envy, murders, drunkenness, revelries, and the like; of which I tell you beforehand, just as I also told you in time past, that those who practice such things will not inherit the kingdom of God.
Rom 12:14-21 Bless those who persecute you; bless and do not curse. Rejoice with those who rejoice, and weep with those who weep. Be of the same mind toward one another. Do not set your mind on high things, but associate with the humble. Do not be wise in your own opinion. Repay no one evil for evil. Have regard for good things in the sight of all men. If it is possible, as much as depends on you, live peaceably with all men. Beloved, do not avenge yourselves, but rather give place to wrath; for it is written, "Vengeance is Mine, I will repay," says the Lord. Therefore "If your enemy is hungry, feed him; If he is thirsty, give him a drink; For in so doing you will heap coals of fire on his head." Do not be overcome by evil, but overcome evil with good.
Rom 13:1-8 Let every soul be subject to the governing authorities. For there is no authority except from God, and the authorities that exist are appointed by God. Therefore whoever resists the authority resists the ordinance of God, and those who resist will bring judgment on themselves. For rulers are not a terror to good works, but to evil. Do you want to be unafraid of the authority? Do what is good, and you will have praise from the same. For he is God's minister to you for good. But if you do evil, be afraid; for he does not bear the sword in vain; for he is God's minister, an avenger to execute wrath on him who practices evil. Therefore you must be subject, not only because of wrath but also for conscience' sake. For because of this you also pay taxes, for they are God's ministers attending continually to this very thing. Render therefore to all their due: taxes to whom taxes are due, customs to whom customs, fear to whom fear, honor to whom honor. Owe no one anything except to love one another, for he who loves another has fulfilled the law.
Mat 17:24 When they had come to Capernaum, those who received the temple tax came to Peter and said, "Does your Teacher not pay the temple tax?" He said, "Yes." And when he had come into the house, Jesus anticipated him, saying, "What do you think, Simon? From whom do the kings of the earth take customs or taxes, from their sons or from strangers?"
Mat 17:26 Peter said to Him, "From strangers." Jesus said to him, "Then the sons are free.
Mat 17:27 "Nevertheless, lest we offend them, go to the sea, cast in a hook, and take the fish that comes up first. And when you have opened its mouth, you will find a piece of money; take that and give it to them for Me and you."
Phil 2:12 Therefore, my beloved, as you have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling; for it is God who works in you both to will and to do for His good pleasure. Do all things without complaining and disputing, that you may become blameless and harmless, children of God without fault in the midst of a crooked and perverse generation, among whom you shine as lights in the world, holding fast the word of life, so that I may rejoice in the day of Christ that I have not run in vain or labored in vain.