forget the problems of the past and look ahead
—I know that our grandfathers were enemies all their lives, but that shouldn’t affect our relationship. Let the dead bury the dead and let’s be friends.

People were amazed at Jesus’ teaching and many wanted to become his disciples, but Jesus told them that following him would require sacrifice. One of these people was a teacher of the Jewish law, who came to him and said, 

“Teacher, I will follow you wherever you go.” Jesus said to him, “Foxes have dens, and the birds in the sky have nests, but the Son of Man has no place to lay his head.” Another of the disciples said to him, “Lord, let me first go and bury my father.” But Jesus said to him, “Follow me, and let the dead bury their own dead [let the dead bury their dead].” (Matthew 8:19-22)

By saying “Let the dead bury their dead,” Jesus was telling the man to let those who were spiritually dead take care of burying those who were physically dead. This was a blunt way of saying that devotion to Jesus needed to come before even duty to family.

exaggerated anguish

—If the team loses the championship game, there will be weeping and gnashing of teeth throughout the whole city.

While Jesus was traveling around, teaching and healing people, a Roman military leader came to him saying that his servant was paralyzed and in pain. Jesus offered to come heal the servant, but the centurion said, “Lord, I am not worthy to have you come under my roof. Instead, just say the word and my servant will be healed.” When Jesus heard his response, he told those with him,

“I tell you the truth, I have not found such faith in anyone in Israel! I tell you, many will come from the east and west to share the banquet with Abraham, Isaac, and Jacob in the kingdom of heaven, but the sons of the kingdom will be thrown out into the outer darkness, where there will be weeping and gnashing of teeth.” Then Jesus said to the centurion, “Go; just as you believed, it will be done for you.” And the servant was healed at that hour. (Matthew 8:10-13)

Jesus message was this: Many non-Jews will choose to follow him, becoming part of God’s kingdom and enjoying the spiritual inheritance of Abraham, Isaac, and Jacob in heaven. But many Jews, the descendants of Abraham, Isaac, and Jacob, will choose not to follow him and will suffer outside the kingdom, in hell.

Here, “gnashing of teeth” means that a person is grinding his teeth together in pain and despair.

a person’s actions show her true character
—My grandmother always taught me that what a person does is more important than what he says. Her favorite sayings were “Actions speak louder than words” and “By their fruits ye shall know them.”

In the Sermon on the Mount, Jesus said,

Watch out for false prophets, who come to you in sheep’s clothing but inwardly are voracious wolves. You will recognize them by their fruit. Grapes are not gathered from thorns or figs from thistles, are they? In the same way, every good tree bears good fruit, but the bad tree bears bad fruit. A good tree is not able to bear bad fruit, nor a bad tree to bear good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire. So then, you will recognize them by their fruit [by their fruits ye shall know them]. (Matthew 7:15-20)

Both by their fruits ye shall know them and wolf in sheep’s clothing talk about recognizing what is really in a person’s heart.

Jesus spoke of sheep and wolves again when he sent his followers out ahead of him to the towns where he was going. Talking about the “harvest” of people entering God’s kingdom, he said,

The harvest is plentiful, but the workers are few. Therefore ask the Lord of the harvest to send out workers into his harvest. Go! I am sending you out like lambs surrounded by wolves [lambs among wolves]. (Luke 10:2,3)

Lamb among wolves now means “an innocent or naive person facing people who will try to take advantage of her or hurt her.”

proper and morally good behavior
—When you move away from your parents, you need to choose the right friends so that you’ll stay on the straight and narrow.

According to Jesus, while following God is the best path, it isn’t the easiest. He said,

Enter through the narrow gate, because the gate is wide and the way is spacious that leads to destruction, and there are many who enter through it. But the gate is narrow and the way is difficult [strait is the gate, and narrow is the way] that leads to life, and there are few who find it. (Matthew 7:13,14)

The strait of the King James Bible is not often used in modern English, which is why it’s now spelled as straight. The words straight and strait not only have different spellings, but they have different definitions, as well. Straight means “not crooked,” while strait means “narrow, confined, or strict.” Strait has not gone away completely, as it still appears in phrases such as strait jacket (“a piece of clothing used to bind a person’s arms tightly to his sides”), and strait-laced (“following a very strict morality or etiquette”).

go after what you want and you’ll get it
—I know you’ve been looking for a new apartment for a long time, but I really believe that if you seek—and don’t give up—ye shall find.

Jesus taught,

Ask and it will be given to you; seek and you will find [seek, and ye shall find]; knock and the door will be opened for you. (Matthew 7:7)

As used today, this phrase usually refers to a person’s own, human efforts to get what he’s looking for, but Jesus was talking about relying on God’s response to prayer:

For everyone who asks receives, and the one who seeks finds, and to the one who knocks, the door will be opened. Is there anyone among you who, if his son asks for bread, will give him a stone? Or if he asks for a fish, will give him a snake? If you then, although you are evil, know how to give good gifts to your children, how much more will your Father in heaven give good gifts to those who ask him! In everything, treat others as you would want them to treat you [all things whatsoever ye would that men should do to you, do ye even so to them], for this fulfills the law and the prophets. (Matthew 7:8-12)

Matthew 7:12 contains the “Golden Rule,” best known in the form “Do unto others as you would have them do unto you.” Golden rule can also be used to mean “the most important principle, which should be followed to gain success,” as in “I believe that the golden rule of learning a foreign language is ‘Don’t compare yourself to others.’”

The idea behind the Golden Rule has been a part of many cultures, even before its inclusion in the New Testament—often in a negative version (i.e., “Do not do . . .”). One example is from the Analects of Confucius (from around 500 BC): “Tsze-kung asked, saying, ‘Is there one word which may serve as a rule of practice for all one’s life?’ The Master said, ‘Is not reciprocity such a word? What you do not want done to yourself, do not do to others.’” (translated by James Legge, 1861)

Before it acquired its current title, the Golden Rule was earlier called the “Golden Law” and “that golden principle of morality.” It is so well known that it is often shortened to simply “Do unto others.”

to present something precious or sophisticated to someone who is unable to appreciate it
—It would be a waste of time to show your invention to the company’s board of directors. They’re so close-minded, it would be casting pearls before swine.

Jesus told his disciples not to present his teachings to those who were openly hostile towards them or who were unable to listen. He instructed them,

Do not give what is holy to dogs or throw your pearls before  pigs [cast ye your pearls before swine]; otherwise they will trample them under their feet and turn around and tear you to pieces. (Matthew 7:6)

correct oneself before criticizing others
—Before the politicians tell us how we need to stop spending money we don’t have, they need to remove the beams from their own eyes.

Jesus warned the people against judging others without first considering one’s own faults, especially when one’s faults are large like planks (“beams”) and theirs are small like specks. The message is this: people first need to take care of their own sins, then they can help others with theirs:

Why do you see the speck in your brother’s eye, but fail to see the beam of wood in your own? Or how can you say to your brother, ‘Let me remove the speck from your eye,’ while there is a beam in your own? You hypocrite! First remove the beam from your own eye [cast out the beam out of thine own eye], and then you can see clearly to remove the speck from your brother’s eye. (Matthew 7:3-5)

it is impossible to pursue two goals that oppose each other
—My friend wants to move to Hollywood to become a famous pop singer, but he also wants to keep his small-town values. I don’t think he can do both. No man can serve two masters.

While teaching about wealth and possessions, Jesus said,

No one can serve two masters [No man can serve two masters], for either he will hate the one and love the other, or he will be devoted to the one and despise the other. You cannot serve God and money [mammon]. (Matthew 6:24)

Mammon comes from an Aramaic word meaning “riches.” (Aramaic was the common language of the Jewish people in Jesus’ day.) Today, mammon means “wealth that causes corruption.”

to kingdom come
to complete destruction
—When the fire reached the dynamite factory, the buildings were blown to kingdom come.

till kingdom come
a very long time; forever
—The line is so long, you’ll have to wait till kingdom come to get your tickets for the concert.

Kingdom come is part of the “Lord’s Prayer,” probably the most well known prayer in the Bible. Jesus taught it to his followers during the Sermon on the Mount:

Our Father which art in heaven, Hallowed be thy name.

Thy kingdom come, Thy will be done in earth, as it is in heaven.

Give us this day our daily bread.

And forgive us our debts, as we forgive our debtors.

And lead us not into temptation, but deliver us from evil: For thine is the kingdom, and the power, and the glory, for ever. Amen. (Matthew 6:9-13 KJV)

The teachings of the Bible say that the kingdom comes in people’s hearts when they follow him, and it will come completely when Jesus returns, the earth is destroyed, and he rules over a new heaven and new earth. It is this second meaning that gives us today’s usages, with “kingdom come” referring to the next world, the afterlife, and the end of the world.

there is confusion, hypocrisy, or a lack of communication
—How can the owner say that the restaurant will open on Monday but the chef says he won’t be ready? The left hand doesn’t know what the right hand is doing!

In much of the Sermon on the Mount, Jesus attacked the hypocrisy of people who followed God’s laws to make themselves look good to others rather than to please God. For example, he said,

Be careful not to display your righteousness merely to be seen by people. Otherwise you have no reward with your Father in heaven. Thus whenever you do charitable giving, do not blow a trumpet before you, as the hypocrites do in synagogues and on streets so that people will praise them. I tell you the truth, they have their reward. But when you do your giving, do not let your left hand know what your right hand is doing [let not thy left hand know what thy right hand doeth], so that your gift may be in secret. And your Father, who sees in secret, will reward you. (Matthew 6:1-4)

According to Jesus, giving to help the poor should not be done to draw attention to oneself. Certainly, if a person should keep a secret from his own hand, then he shouldn’t tell other people what he is doing.

While this phrase is often used in modern English to describe a group or individual whose plans or actions are inconsistent, another form can also be used as a warning to keep something secret: Don’t let the left hand know what the right hand is doing.