Credulity (noun)

1. The tendency to believe too readily, especially without proper or adequate evidence.
2. The state of being easily fooled or deceived.
3. The willingness to accept as true or real without sufficient evidence.

Origin:

Late 16th century: from latin credulitas, from credulus "easily believing", from credere "to believe".

Examples:

1. He was criticized for his credulity, he believed everything he was told.
2. The email scam preyed on the credulity of the elderly.
3. Many people were taken in by the scam because of their credulity.
4. The speaker took advantage of the audience's credulity, making false claims.
5. His credulity was his weakness, he always believed in everything he was told without questioning.