Debemos luchar contra el odio.

Debemos is the 1st person plural form of deber in the present tense.

• deber = to must / to have to / to should / to ought to
• debemos = we must / we should / we ought to

In this sentence, it most naturally means we must or we should, with a strong sense of moral obligation.

Because after deber, Spanish normally uses the infinitive.

Pattern:

• deber + infinitive

So:

• Debemos luchar = We must fight

This is similar to English must fight, where you do not say must to fight.

Other examples:

• Debo estudiar = I must study
• Debemos ayudar = We must help

In Spanish, after modal verbs like deber, poder, or querer, you usually go directly to the infinitive.

So:

• debemos luchar = we must fight
• not debemos a luchar

This is one of those places where English and Spanish structure differ slightly.

Contra means against.

So:

• luchar contra = to fight against

It is a very common combination in Spanish:

• luchar contra la pobreza = to fight against poverty
• luchar contra la injusticia = to fight against injustice

Because Spanish often uses the definite article with abstract nouns when speaking about them in a general sense.

So:

• el odio = hatred
• la paz = peace
• la libertad = freedom

In English, we often leave the article out with abstract nouns, but Spanish frequently keeps it.

That is why contra el odio sounds natural, while contra odio would sound incomplete or wrong here.

Good question. Odio can be:

1. the noun hatred
2. the verb form I hate from odiar

The article el makes it clear that here it is a noun:

• el odio = hatred

Compare:

• Odio la violencia. = I hate violence.
• Debemos luchar contra el odio. = We must fight hatred.

So the article helps remove ambiguity.

Because Spanish often omits subject pronouns when the verb form already shows who is doing the action.

• debemos already clearly means we
• so nosotros is unnecessary unless you want emphasis or contrast

Both are possible:

• Debemos luchar contra el odio.
• Nosotros debemos luchar contra el odio.

The second one sounds more emphatic, like We must fight hatred.

Yes, absolutely. That is also natural Spanish.

Both mean something like We have to / must fight hatred, but there can be a slight nuance:

• debemos luchar often sounds a bit more moral, formal, or ethical
• tenemos que luchar can sound a bit more practical or everyday

In many contexts, though, they are very close.

Because in Spanish, only two common contractions happen:

• a + el = al
• de + el = del

But:

• contra + el stays contra el

So:

• contra el odio is correct
• there is no contraction here

Yes, but the original order is the most neutral and natural:

• Debemos luchar contra el odio.

You might also see:

• Contra el odio debemos luchar.

That version is more emphatic or literary, because it puts focus on contra el odio first. For normal use, the original sentence is the best choice.

A simple pronunciation guide is:

deh-BEH-mos loo-CHAR KON-tra el OH-dyo

A more Spain-focused IPA version is:

[deˈβemos luˈtʃaɾ ˈkontɾa eˈloðjo]

A few useful notes:

• debemos: the stress is on be
• luchar: the stress is on the last syllable because it ends in r
• contra: stress on con
• odio has two syllables: o-dio
• in connected speech, el odio often sounds quite smooth together

No. Luchar is very natural, but other verbs are possible depending on the tone:

• luchar contra el odio = fight against hatred
• combatir el odio = combat hatred
• enfrentarse al odio = confront hatred

Luchar contra is especially common when talking about social problems, injustice, discrimination, and similar ideas, so it fits this sentence very well.