affirmation

I.e.: In law, an affirmation is a solemn declaration allowed to those who conscientiously object to taking an oath. An affirmation has exactly the same legal effect as an oath but is usually taken to avoid the religious implications of an oath; it is thus legally binding but not considered a religious oath. Some religious minorities hold beliefs that allow them to make legally binding promises but forbid them to swear an oath before a deity. Additionally, many decline to make a religious oath because they feel that to do so would be valueless or inappropriate, especially in secular courts. In some jurisdictions, an affirmation may be given only if such a reason is provided. https://en.wikipedia.org/wiki/Affirmation_in_law