What is Faith?

Legal Definition
Faith is confidence or trust in a person or thing; or the observance of an obligation from loyalty; or fidelity to a person, promise, engagement or it may refer to a particular system of religious belief, such as in which faith is confidence based on some perceived degree of warrant. The term 'faith' has numerous connotations and is used in different ways, often depending on context.
-- Wikipedia
Legal Definition
Probity; good faith is the very soul of contracts. Faith also signifies confidence, belief; as, full faith and credit ought to be given to the acts of a magistrate while acting within his jurisdiction. Vide Bona fide.
-- Bouviers Law Dictionary
Legal Definition
1. Confidence; credit; reliance. Thus, an act may be said to be done "on the faith" of certain representations.

2. Belief; credence; trust. Thus, the constitution provides that "full faith and credit" shall be given to the judgments of each state in the courts of the others.

3. Purpose; intent; sincerity; state of knowledge or design. This is the meaning of the word in the phrases "good faith" and "bad faith." In Scotch law. A solemn pledge; an oath. "To make faith" is to swear, with the right hand uplifted, that one will declare the truth. 1 Forb. Inst pt. 4, p. 235.
-- Black's Law Dictionary