Matthew is talking here about the thoughts that lead one to commit a crime. For emphasis, he gives two examples that can better be understood by looking at verse 5:25 in the context of a longer passage, Matthew 5:21-28, which I will discuss in two parts.
Matthew 5:21-26: "You have heard that it was said to your ancestors,
'You shall not kill; and whoever kills will be liable to judgement.'
But I say to you, whoever is angry with his brother will be liable to
judgement, and whoever says to his brother, 'Raqa,' will be answerable
to the Sanhedrin, and whoever says, 'You fool,' will be liable to
Therefore, if you bring your gift to the altar, and there recall that
your brother has anything against you, leave your gift there at the
altar, go first and be reconciled with your brother, and then come and
offer your gift. Settle with your opponent quickly while on the way to
court with him. Otherwise your opponent will hand you over to the
judge, and the judge will hand you over to the guard, and you will be
thrown into prison. Amen, I say to you, you will not be released until
you have paid the last penny.
The Greek word used here for brother is gender neutral and does not necessarily imply siblings. Anger can inflame a situation and lead to killing, so Jesus says:
- Whoever is angry with his brother will be liable to judgement
- Whoever says to his brother, Raqa, ['empty'] will be answerable to the Sanhedrin
- Whoever says, 'You fool,' will be liable to fiery Gehenna.
Instead, verse 5:25 says that if someone has anything against you, to be reconciled with him and reach a settlement before this goes to court. Otherwise, the judge may find against you and hand you over for imprisonment.
Matthew 5:27-28: "You have heard that it was said, 'You shall not
commit adultery.' But I say to you, everyone who looks at a woman with
lust has already committed adultery with her in his heart.
Matthew then says that just as anger can lead to killing, so also lust can lead to adultery. He says that anyone who looks at a woman with lust has already committed adultery in his heart.
So, in real life: hold your temper and avoid inflaming a situation, particularly if you may be in the wrong. Note that this is equally true whether your opponent is taking you to court or simply in dispute with you. In the second example, do not lust after a woman if this would result in adultery, because your very thoughts are adulterous.