How to Say "to sin" in Spanish
The Spanish word for “to sin” is “pecar” — B1 level.
English → SpanishB1
verbB1
to commit a religious or moral offense

Examples
Dice la religión que todos podemos pecar.
Religion says that we can all sin.
No quiero pecar contra mis principios.
I don't want to sin against my principles.
Es humano pecar, pero es divino perdonar.
To sin is human, but to forgive is divine.
The 'k' sound spelling change
To keep the 'k' sound in the word, the 'c' changes to 'qu' whenever the next letter is an 'e' (like in the 'I' form of the past tense: 'pequé').
Using 'contra'
When you want to say who or what you are sinning against, use the word 'contra' right after 'pecar'.
Spelling error in the past
Mistake: “Yo pecé ayer.”
Correction: Yo pequé ayer. (Use 'qu' to keep the hard 'k' sound before an 'e'.)
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