There are some religions that believe, or have faith (same word) that there is only one God. The Jews, the Muslims, and even some pagan religions, are monotheistic, or nearly so. They believe that there is only one God. That is good, so far as it goes, but as James points out, merely having faith in this one aspect of the Creator, that He is one, does not qualify one for salvation. The devils, the fallen angels, are also monotheists, because they know (from experience) that there is only one Elohim.
The Scriptures, however, speak about a very special kind of faith, a faith in, and of, the Savior; and this is the faith that leads to eternal life. We read, “But the Scripture hath concluded [grouped together] all under sin, that the promise by faith of Yahshua the Messiah might be given to them that believe.” (Gal 3:22) And, “Here is the patience of the saints: here are they that keep the commandments of God, and the faith of Yahshua.” (Rev 14:12)
Nowadays, even this kind of faith is poorly understood, because people will agree with the first part of the definition, that it is a conviction that something is true. They leave out, unfortunately, the second weight of meaning this term carried in the ancient mind, that belief was also a motivating factor behind actions. It is not enough, in Bible terminology, to accept something as true intellectually, and particularly so when it comes to the faith of Yahshua. Some will quote Romans 10:9 and think that this is the whole thought: “That if thou shalt confess with thy mouth the Lord Yahshua, and shalt believe in thine heart that God hath raised Him from the dead, thou shalt be saved.”
But Paul goes on to explain exactly what he means by “believe in thine heart,” saying, “For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.” (Rom 10:10) True belief, according to the apostle, leads to two outward signs of its existence: Righteousness, which is “correctness of thinking feeling, and acting,” and Confession, an open testimony of our state. In other words, is religion, according to Paul, a “personal” thing in that it is to be kept private?
Not at all… the religion of Christ must be the most public of things, and only those who are ashamed of the things they claim to be true will use, as an excuse to remain neutral or silent, the statement that “Faith is a personal thing.” In a sense the statement is true, because we must accept it as individual persons, being individually saved… but that is where the individual nature of it ends. After that we are a part of a community, a fellowship of earthly saints with “an innumerable company of angels,” (Heb 12:22) and a royal nation whose greatest obligation is to teach the world what it knows about Yahweh, and openly so.