Faith is interesting. It is many layered, with great depth to it if you care to spend enough time thinking about it. Some mix it up with grace or belief and consider them all of a similar thing. And while that may be close enough for teaching Sunday School children, it has its own distinct nature that rewards further investigation.
A definition would be useful at this point. If we are to speak of something, then knowing whereof we speak is always appropriate. Definitions of faith abound. Webster's Dictionary is always a good place to start, so let's see what they say:
Faith: allegiance to duty or a person; loyalty ... belief and trust in and loyalty to God ... something that is believed especially with a strong conviction.
For reasons that you'll see in a moment, allow me to also include the definition of "belief":
Belief: A state or habit of mind in which trust of confidence is placed in some person or thing.
That's good, but it doesn't seem to perfectly capture the understanding of faith that years of living it brings. Time to turn to the Greek language and see what we find when we look at faith there. The Greek words most often associated with "faith" are pisteuo and pistis. Pisteuo is usually translated as "believe", while the noun form pistis is normally translated as "faith".
pisteuo (Amplified Bible): To adhere to, trust, to have faith in, to rely on.
pisteuo (W.E. Vine): To believe, to be persuaded of and hence, to place confidence in, to trust, signifies, in this sense of the word, relience upon, not mere credence.
pistis (W.E. Vine): Primarily, firm persuasion, a conviction based upon hearing.
From these definitions I think that the nature of faith starts to emerge. Faith is a firm persuasion or trust that we can have. It is a static thing, hence the noun form of pistis. Yet faith can also be an active thing, and that we see in pisteuo and the use of the English word "believe". Believing is faith in action. Believing is doing because of faith.
Faith is progressive. We know this because of the references and admonitions to grow in faith. Everyone starts with a given portion of faith.
For I say, through the grace given unto me, to every man that is among you, not to think of himself more highly than he ought to think; but to think soberly, according as God hath dealt to every man the measure of faith.
And then we have the opportunity to increase our faith.
So then faith cometh by hearing, and hearing by the word of God.
What then is the purpose of faith? The Lord must surely have had a design to equip all with that initial portion of faith. We find that faith is how we appropriate the grace that the Lord brings to the human race.
But now the righteousness of God without the law is manifested, being witnessed by the law and the prophets; Even the righteousness of God which is by faith of Jesus Christ unto all and upon all them that believe: for there is no difference: For all have sinned, and come short of the glory of God; Being justified freely by his grace through the redemption that is in Christ Jesus:
Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God; To declare, I say, at this time his righteousness: that he might be just, and the justifier of him which believeth in Jesus.
God's grace was poured out in the redemption, the sacrifice, of Jesus Christ. He is our propitiation, the one who made the ultimate sacrifice on our behalf to pay the price of our sins. It is faith that enables us to claim that propitiation by our belief in Jesus. Knowing that belief is faith in action, our active faith in Jesus Christ as Messiah who died for our sins brings the righteousness of God upon us.
Faith is a life changing power. We generally find it in two forms. The first is Saving Faith and the second is Continuing Faith.
Bro. Bernard explains saving faith as acceptance of the gospel of Jesus Christ as the sole means of our salvation and appropriation (application) of that gospel to our lives by obedience to its requirements. That's a wonderful definition and I believe it's accurate, but it's not how I want to describe saving faith.
I believe that saving faith is faith that motivates you to that which is required to be saved. It is enough faith to obey the teaching that the apostle Peter gave on the day of Pentecost when the Spirit of God was first poured out. It is faith that drives a person to repent of their sins, to request baptism by immersion in the name of Jesus and then to seek for the infilling of the Holy Ghost, with the evidence of speaking in tongues. That's what I call saving faith.
Continuing faith is simply saving faith that does not stop. The initial salvation experience is undertaken one time, but the faith that drove a person to seek salvation can also drive a person to live a life pleasing to the Lord.
Faith, powerful as it is, acts as a catalyst when combined with obedience or works. Faith takes obedience and works to their highest levels. It can be argued that without faith they are nothing, so a firm faith is to be sought first so that obedience and works may be layered on top.
Paul had much to say about obedience. Including that obedience was one of the criteria for him being an apostle.
By whom we have received grace and apostleship, for obedience to the faith among all nations, for his name:
Many people have had the gospel message preached to them, yet there are those who have heard it who have not obeyed it. Their portion of faith allowed them to hear it, perhaps even to understand it, but their obedience was lacking and thus they are lost.
But they have not all obeyed the gospel. For Esaias saith, Lord, who hath believed our report?
The mystery of the Messiah and the fusing of God and flesh, was explicitly taught so that the nations of the world would be obedient to their faith.
But now is made manifest, and by the scriptures of the prophets, according to the commandment of the everlasting God, made known to all nations for the obedience of faith:
Luke tells us that many of the priests in Jerusalem were obedient to their faith.
And the word of God increased; and the number of the disciples multiplied in Jerusalem greatly; and a great company of the priests were obedient to the faith.
And the writer of Hebrews directly ties salvation and obedience together. There is no salvation without obedience.
And being made perfect, he became the author of eternal salvation unto all them that obey him;
Works are another natural pairing with faith. Where there is saving or continuing faith, there is naturally expected to be good works. Paul explained this in his letter to Titus.
This is a faithful saying, and these things I will that thou affirm constantly, that they which have believed in God might be careful to maintain good works. These things are good and profitable unto men.
And it doesn't take much exposure to the book of James to know that James robustly expressed a direct relationship between works and faith. James goes as far as to explain that your salvation is at risk if you don't have works.
What doth it profit, my brethren, though a man say he hath faith, and have not works? can faith save him?
Not that we are saved by works. No, absolutely not. But, works are an external evidence that we have experienced saving faith and have continuing faith. This is not unlike speaking in tongues being the initial and external evidence that someone has received the Holy Ghost. We can know that sufficient faith is in someone's life by observing their works.
Even so faith, if it hath not works, is dead, being alone. Yea, a man may say, Thou hast faith, and I have works: shew me thy faith without thy works, and I will shew thee my faith by my works. Thou believest that there is one God; thou doest well: the devils also believe, and tremble. But wilt thou know, O vain man, that faith without works is dead? Was not Abraham our father justified by works, when he had offered Isaac his son upon the altar? Seest thou how faith wrought with his works, and by works was faith made perfect? And the scripture was fulfilled which saith, Abraham believed God, and it was imputed unto him for righteousness: and he was called the Friend of God. Ye see then how that by works a man is justified, and not by faith only. Likewise also was not Rahab the harlot justified by works, when she had received the messengers, and had sent them out another way? For as the body without the spirit is dead, so faith without works is dead also.
Let me try to wrap this up neatly and put a bow on it.
Faith is a firm certainty in something. Here I am speaking of biblical faith, so that would be a firm certainty in God: his existance, his word, his power and his offer of salvation to this fallen world (otherwise known as grace). That firm certainty naturally expresses itself with actions. We call these saving faith, continuing faith and good works. Saving faith is faith in action, also known as belief, and it motivates us to seek a full and deep relationship with the Lord. Continuing faith is our understanding of the necessity to maintain that relationship and good works are kindnesses that flow out of the saved believer towards their fellow man.
It is also commonly explained that faith is how we access the grace of God, but where is the fun in explaining something so sucinctly when you can use a thousand words instead?