Nie stracę wiary.

Polish often does not use a separate word like will.

Here, stracę is from the verb stracić (to lose in a perfective sense, meaning a complete loss). Perfective verbs in Polish use present-type endings to talk about the future.

So:

• stracę = I will lose
• literally, it looks like a present-form ending, but its meaning is future because the verb is perfective

This is a very common pattern in Polish.

The dictionary form is stracić.

A quick breakdown:

• stracić = to lose
• stracę = I will lose

The ending -ę shows 1st person singular, so the subject is I.

Because wiary is a declined form of wiara.

• wiara = the basic dictionary form, called the nominative
• wiary = here, the genitive singular

You cannot leave the noun as wiara here, because the sentence structure requires a different case.

This is because of negation.

Without negation, you would normally say:

• Stracę wiarę. = I will lose faith.

Here, wiarę is the accusative object.

But after nie, Polish very often changes the direct object to the genitive:

• Nie stracę wiary. = I will not lose faith.

This is a classic Polish pattern often called the genitive after negation. In this sentence, wiary is the standard form.

Because Polish usually drops subject pronouns when they are already clear from the verb form.

• stracę already tells you I because of the ending -ę

So:

• Nie stracę wiary. = normal, natural
• Ja nie stracę wiary. = also possible, but more emphatic, like I will not lose faith

Polish does this much more often than English.

Because with finite verb forms, nie is normally written as a separate word in Polish.

So:

• nie stracę = correct

This is the normal spelling pattern for negated verbs.

The difference is mainly aspect and time sense.

• Nie stracę wiary = I will not lose faith
  This uses a perfective verb and points to a future completed event.

• Nie tracę wiary = I am not losing faith / I do not lose faith
  This uses the imperfective verb tracić and suggests an ongoing process, habit, or present situation.

So the sentence with stracę sounds more like a firm statement about the future.

Yes. Polish word order is fairly flexible.

The neutral order here is:

• Nie stracę wiary.

But you could also say:

• Wiary nie stracę.

That version puts more emphasis on wiary (faith), as if contrasting it with something else.

So the basic meaning stays similar, but the focus or emphasis changes.

Because Polish has no articles.

English needs words like:

• a
• the

Polish does not. So wiary can mean something like faith, and the exact nuance depends on context.

That is completely normal in Polish.