Hebrews 11:1 Now faith is the assurance of things hoped for, the conviction of things not seen.
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That defines and demonstrates saving faith well enough for me. Understanding the convincement/conviction/persuasion of the Holy Spirit and the preached Word, I fully committed my trust unreservedly that JESUS SAVES, and saved me immediately upon my earnest plea alone, and placed me on the path of progressive sanctification according to His Will and my submission to it.
Of late, I've tried to stay away from using the words "faith" and "belief" or "believer" or "Christian" because all these are so overused that they have become so trite or meaningless to so many that use them profusely. not really understandng their definition or meaning in talking about spiritual matters.
My own preference is to converse in terms that still have clear distinction, not ambiguous at all, whilst attempting to discuss the doctrine of the apostles as given by their Savior first-hand.