John 3:36 He that believeth on the son hath everlasting life: and he that believeth not the son shall not see life: but the wrath of God abideth on him.
The doctrine of belief in Jesus is the single most important issue in all of Christendom. According to the gospel of John (as well as the rest of the scriptures) it is the only way that salvation can come, without belief the wrath of God abides on every person. If this is all so, than it is expedient for us to understand what it is to truly believe. Even in the New Testament, error was not only sneaking into the church but some of it was storming in. In order to lay down a clear and concise statement of what Christians should believe and how they should interpret difficult portions of scripture, christian leaders would gather together in councils and write a creed articulating a doctrine. One such doctrine that was being disputed was this issue of belief, what did it mean to believe in the Son? Is there a difference between believing in many secular things and believing in Christ? This is what was decided hundreds of years ago by these giants of the faith, and has been held by orthodox Christianity ever since.
The first kind of belief was given the Latin term notitia, notitia is the word that we derive our verb "to note" from. This type of belief means simply to understand what is being said, I say to you that a chair will hold you up, and you understand what a chair is, you understand what it means to sit, and you understand what it means to hold up. You notitia what I'm saying, you understand it. However, notitia is not saving belief, there are many atheists that notitia the gospel, they understand what is being said, but that does not save them.
The second kind of belief is another Latin word, assensus. You can probably tell that this is where we get our word "assent" from, it means that you agree that what I'm saying is true. To assensus the gospel means that you leave the realm of pure intellectualism and take a small step of faith. Not only do you understand what I mean when I say the chair will hold you up, but you actually agree that the chair has the ability to hold you up. Unfortunately, there are many filling the pews of our churches who assensus the gospel, but it means no more to them than the fact that Napoleon lost the battle of Waterloo. Assensus by itself is not saving belief either, I know a man that agrees with everything I say about the gospel, but will have nothing to do with it personally. By his own admission he is heading to hell, yet he refuses to believe in the gospel.
The last part of saving belief is known as fiducia, the English word fidelity springs from this term. This is the belief that is spoken of in John 3:36, while it is not possible to have it without the first two, it is the essential, final piece to saving belief. To fiducia the gospel it becomes personal, you actually sit in the chair that you have already said you believed would hold you up. A person that has this kind of belief in the gospel is eternally secure in Christ, there is no if, ands, or buts, for a person that fiducias the gospel. If you are trusting in anything else outside of Christ for your conversion, (i.e. baptism, church membership, good works, Communion) you do not fiducia the gospel. While all of those things are critical components for someone who is already saved, they have no bearing on your whether God saves you or not. I pray that your belief goes beyond that of notitia and assensus and that you have put complete fiducia in the Son, so that you may escape the wrath of God and have everlasting life.