WHAT IS FAITH?
Faith is one of those words that is difficult to tie down to one simple definition.
POPULAR DEFINITIONS:
According to a modern dictionary, faith is "unquestioning belief that does not require proof or evidence." As it regards the faith found in the Bible, this is simply not true. A. A. Hodge truly said, "Faith must have adequate evidence, else it is mere superstition." Faith is not the opposite of fact or of scientific knowledge. The evidences of faith may operate differently than those of science, but they are there.
Someone else has come up with an acronym for FAITH:
Forsaking
All
I
Take
Him
This is an good illustration to use when teaching about faith, but as with most definitions of this kind, it still comes far short.
Many Bible students will give Hebrews 11:1
as the definition for faith and leave it at that. Hebrews 11:1
states, "Now faith is the substance of things hoped for, the evidence of things not seen." However, even though this is the form defintions are given in, this verse is more of an expression of the power and importance of faith than it is a definition of faith. In fact, one already needs to know what faith is before this verse will make much sense to them. This makes this verse a frustrating answer to someone who is trying to get a handle on the foundational meaning of faith.
BIBLE DEFINITION:
If you want a short definition of faith, it could be this: taking God at His word. It is true that our faith is in God. But we do not properly know the God we should believe in or know how to believe in Him unless He tells us in His word. This is why Paul says in Romans 10:17
, "So then faith cometh by hearing, and hearing by the word of God." Biblical faith is not an "unquestioning belief that does not require proof or evidence" (Webster's New World Dictionary). It is full confidence in God's word. FAITH accepts God's word (His promises and His warnings) as FACT and acts accordingly. Since there are many evidences that the word of God is true, this is not a blind leap of faith. It is rather an intelligent, holy reaction to the wondrous words of God.
Now it is true that faith is much more than a mental acceptance of something as true; it also involves a trust in or reliance on that something. The Reformers of the sixteenth and seventeenth centuries had a good approach to faith. They taught what they called the three aspects of faith. Here are the three aspects of faith:
1. Knowledge. Faith begins with a knowledge of what it is that should be believed. For instance, if someone knows that the gospel of Christ refers to the death, burial, and resurrection of Christ according to the scriptures (see 1 Corinthians 15:1-4), they have knowledge. However, it is possible for someone to know what the gospel is without believing it to be true. Therefore:
2. Assent. Knowledge is not enough. The person must also believe that the object of faith is true. To reach this level of faith, the person must know what the gospel is (knowledge) and believe it to be true (assent). But this is still not enough for salvation. That takes us to the third aspect of faith.
3. Trust. Trust refers to a personal commitment to and reliance upon an object of faith. In salvation, the sinner must know that Jesus died for him and rose again from the dead (knowledge) and he must accept that these facts are true (assent). However, he is still not saved until he relies on these facts as the basis for his personal salvation. Let me give you a couple of illustrations to help you understand these three aspects.

Good post Brother Deacon,
You have offered many wonderful definitions of faith, I would also like to think of faith as the means by which one exercises trust in the object of the understanding.
Essentially, a person exercises faith by having a trust relationship with a person. But, faith also involves a modicum of understanding (where understanding is a form of propositional knowledge) about the person who is trusted.
It is just as important to have faith in oneself as well as faith in God, as faith is part of the development stage of growth. Example: Before an infant child learns how to walk the child puts his or her faith (trust) in a person, usually the parent or other adult that teaches them. Once the child learns (knows) how to walk they know longer put their faith in someone else that they will be able to walk, they use the principles of walking to move them. Faith is what you need to begin growing, to grow, and to keep on growing and developing.
The following Bible verses can also be helpful when teaching about faith.
Habakkuk 2:4 "behold, his soul which is lifted up is not upright in him: but the just shall live by faith."
Matt 9:29 " Then touched he their eyes, saying, According to your faith be it unto you."
Romans 1:17 " For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith."
Rom 3:3 "For what if some did not believe? shall their unbelief make the faith of God without effect ?"
The Qu'ran also states:
Chapter 2:28 How can ye reject the faith in God?- seeing that ye were without life, and He gave you life; then will He cause you to die, and will again bring you to life; and again to Him will ye return.
Chapter 10:009 Those who believe, and work righteousness,- their Lord will guide them because of their faith: beneath them will flow rivers in gardens of bliss.
Chapter 16:97 Whoever works righteousness, man or woman, and has Faith, verily, to him will We give a new Life, a life that is good and pure and We will bestow on such their reward according to the best of their actions.
Chapter 98:007 Those who have faith and do righteous deeds,- they are the best of creatures.
If Faith is the substance of things hoped for, and the evidence of things not seen; then as children of the Most High, we would be amiss, to be without faith no matter what religious affiliation we identify with. For belief and faith are what we are made from. Take away faith, and we have nothing. We must have the same faith to be able to truly unite (one God).