I get my understanding of Faith from the Greek Scriptures. I have a Strong's expanded exhaustive concordance of the Bible and Pisteuo #4100 says - to have faith (in, upon, or with respect to, a person or thing), to entrust (especially one's spiritual well being to Christ). It goes on to say, pisteuo means not just to believe, but also to be persuaded of; and hence, to place confidence in, to trust, and signifies, in this sense of the word, reliance upon.
*So saving faith is (belief, trust, reliance) in Jesus Christ for salvation.