Paul taught Timothy,
"Let no man despise thy youth; but be thou an example of the believers, in word, in conversation, in charity, in spirit, in faith, in purity." (1 Timothy 4:12)
So obviously we are to be an example to the unbelievers of what a believer is. By the way we talk, what we talk about, how we treat others, by the way we pray, how we exercise our faith in God, in how we live a pure life.
Jesus taught from the Sermon on the Mount,
3 Blessed are the poor in spirit: for theirs is the kingdom of heaven.
4 Blessed are they that mourn: for they shall be comforted.
5 Blessed are the meek: for they shall inherit the earth.
6 Blessed are they which do hunger and thirst after righteousness: for
they shall be filled.
7 Blessed are the merciful: for they shall obtain mercy.
8 Blessed are the pure in heart: for they shall see God.
9 Blessed are the peacemakers: for they shall be called the children
10 Blessed are they which are persecuted for righteousness’ sake: for
theirs is the kingdom of heaven.
11 Blessed are ye, when men shall revile you, and persecute you, and
shall say all manner of evil against you falsely, for my sake.
12 Rejoice, and be exceeding glad: for great is your reward in heaven:
for so persecuted they the prophets which were before you.
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.
14 Ye are the alight 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 alight so shine before men, that they may see your good
works, and glorify your Father which is in heaven." (Matthew 5:13)
If I understand what Jesus is saying, He is telling us to mourn with those who mourn, visit the sick and imprisoned, be a light, a city on a hill, the salt of the earth to give flavor to the community.
Jesus once was asked, "Who is my neighbor?" Upon which, the Lord gave
the parable of the Good Samaritan and then asked again,
"Which now of these three, thinkest thou, was neighbour unto him that
fell among the thieves?
And he said, He that shewed mercy on him. Then said Jesus unto him,
Go, and do thou likewise." (Luke 10:29-37)