Found 20 stronger alternatives to upgrade your writing.
Believe a person is telling the truth
Nuance: Confidence in someone
Use trust when it is about a person being reliable.
Boring
I believe you are telling me the truth.
Better
I trust you to tell me the truth.
Slang: do not accept a story
Nuance: Skeptical
Casual slang; means you do not believe it.
Boring
I do not believe that excuse.
Better
I do not buy that excuse.
Weak belief or guess
Nuance: Uncertain
Used for a mild guess (not 100 percent sure).
Boring
I believe the test is tomorrow.
Better
I suppose the test is tomorrow.
Not sure (estimate)
Nuance: Uncertain
Common when you are unsure.
Boring
I believe she is running late.
Better
I guess she is running late.
Accept as true (facts)
Nuance: Factual agreement
Good for facts and evidence.
Boring
He believed the evidence was true.
Better
He accepted the evidence as true.
Think something is true (often negative)
Nuance: Doubtful
Often used when you think something bad may be true.
Boring
I believe he is not being honest.
Better
I suspect he is not being honest.
Regard as (opinion)
Nuance: Personal judgment
Use when you are judging or describing someone.
Boring
I believe she is a great friend.
Better
I consider her a great friend.
Suppose without proof
Nuance: Presumptive
Use when you are guessing based on what seems likely.
Boring
I believe the meeting starts at three.
Better
I assume the meeting starts at three.
Be completely sure (base verb)
Nuance: Certain
Often appears as convinced in real sentences.
Boring
I believed he was telling the truth.
Better
I was convinced he was telling the truth.
Hold an opinion (formal)
Nuance: Steady opinion
Formal way to state an opinion.
Boring
She believes that recess matters.
Better
She holds the view that recess matters.
Believe a claim is true (formal)
Nuance: Doubt or acceptance
More formal; often used with stories or claims.
Boring
The teacher did not believe his story.
Better
The teacher did not credit his story.
Believe gullibly
Nuance: Gullible
Often suggests being tricked or too trusting.
Boring
He believed the rumor without checking.
Better
He swallowed the rumor without checking.
Depend on something being true
Nuance: Dependable
Use when you depend on someone keeping a promise.
Boring
I believe his word when he promises.
Better
I rely on his word when he promises.
Infer from clues (polite)
Nuance: Inferred
Polite and slightly formal.
Boring
I believe you are busy right now.
Better
I gather you are busy right now.
Informal: think/assume
Nuance: Reasoned guess
Casual; common in speech.
Boring
I believe we should start early.
Better
I figure we should start early.
Guess politely
Nuance: Uncertain
Polite guess; not certain.
Boring
I believe the bus will be late.
Better
I imagine the bus will be late.
Deep trust (often emotional)
Nuance: Deep trust
Stronger than believe; can feel emotional or spiritual.
Boring
I believe we can fix it.
Better
I have faith that we can fix it.
Strong personal trust (endorsement)
Nuance: Strong endorsement
Used for strong personal confidence in something.
Boring
I believe this study method works before tests.
Better
I swear by this study method before tests.
Informal/regional: think
Nuance: Casual opinion
Sounds casual and regional.
Boring
I believe we will finish on time.
Better
I reckon we will finish on time.
British: think/guess (also want)
Nuance: Old-fashioned tone
In British English it can mean think/guess.
Boring
I believe he forgot the meeting.
Better
I fancy he forgot the meeting.