Now 
Faith
is
the substance of things
hoped for, the evidence
of things not
seen.
(Hebrews 11:1)    


...Through faith we understand that
the worlds were framed by the word of God, so that things which are seen were not made of  things which do appear...But without faith, it is impossible to please Him: for he that cometh to God must believe that He is, and that He
is a rewarder of them that
diligently seek Him
Heb 11, Verses   
3 and 6  

To Have Faith
is,
To Trust, To Believe, To Obey.

We have 'faith' or 'no faith' in the words people tell us. 

We 'have faith' in God and in the Bible. 

We have 'saving faith' by firmly believing in
Jesus Christ, His Word, and His Promises. 

We are 'faithful' to others by doing
our duty and fulfilling
our  promises.  
Faith is also:
The promises of God, or His truth and faithfulness...

"For what if some did not believe?  Shall their
unbelief make the faith
of God without
effect?"
Ro 3:3  
Faith is also:
The object of belief; a doctrine or
system of doctrines believed; a system
of revealed truths received by christians. (Webster's 1828)
"They heard only, that he who persecuted us in times past now preacheth the faith which
he once destroyed." 
Ga 1:23