MAT. 17 V 20

20And Jesus said unto them, Because of your unbelief: for verily I say unto you, If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you. 

Notice lack of faith is associated with lack of belief. It is a requirement of God that we believe him, there is no faith without belief.

LUKE 17 V 6.

6And the Lord said, If ye had faith as a grain of mustard seed, ye might say unto this sycamine tree, Be thou plucked up by the root, and be thou planted in the sea; and it should obey you.

If we just take those two verses then it is quite obvious that no one has any faith whatsoever, have you ever seen anyone move a mountain. Some more about faith is learned from the following verse

LUKE 17 V 5.

5And the apostles said unto the Lord increase our faith.

Why did the apostles want their faith increased if they could have moved mountains? They had faith but wanted it increased. This shows that they did not have enough faith. Notice the answer from Jesus.

LUKE 17 V 6

6And the Lord said, If ye had faith as a grain of mustard seed, ye might say unto this sycamine tree, be thou plucked up by the root, and be thou planted in the sea; and it should obey you.

Notice that faith is likened to a mustard seed, which starts extremely small and grows extremely large.

MAT. 13 V 31

31Another parable put he forth unto them, saying, The kingdom of heaven is like to a grain of mustard seed, which a man took, and sowed in his field: 32Which indeed is the least of all seeds: but when it is grown, it is the greatest among herbs, and becometh a tree, so that the birds of the air come and lodge in the branches thereof.

It is obvious that people do not have enough faith to move mountains. We have to have our faith increased by God. By associating our faith to a mustard seed it is extremely plain that if we have a minute amount of faith we will eventually have great faith as we grow in grace and knowledge. Our faith is dependent on believing the Bible

Some characteristics associated with little faith are as follows:
Being afraid. [the fearful will not be in Gods Kingdom Rev. 21 v 8]

MAT. 8 V 26

26And he saith unto them, Why are ye fearful, O ye of little faith? Then he arose, and rebuked the winds and the sea; and there was a great calm. 

Doubt.

MAT. 14 V 31.

31And immediately Jesus stretched forth his hand, and caught him, and said unto him, O thou of little faith, wherefore didst thou doubt?

Lack of understanding.

MAT 16 V 8,9.

8Which when Jesus perceived, he said unto them, O ye of little faith, why reason ye among yourselves, because ye have brought no bread? 9Do ye not yet understand, neither remember the five loaves of the five thousand and how many baskets ye took up? 

Faith can be increased.

LUKE 17 V 5.

5And the apostles said unto the Lord increase our faith.

The just shall live by faith.

ROM. 1 V 17.

17For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith.

Faith comes from hearing the word of God.

ROM. 10 V 17

17So then faith cometh by hearing, and hearing by the word of God.

Faith can not be feigned.

1 TIM. 1 V 5.

5Now the end of the commandment is charity out of a pure heart, and of a good conscience, and of faith unfeigned.

We must not waver in our faith.

JAMES 1 V 6.

6But let him ask in faith, nothing wavering. For he that wavereth is like a wave of the sea driven with the wind and tossed.

Faith without works is dead

JAMES 2 V 18,26.

26For as the body without the spirit is dead, so faith without works is dead also.

Our faith will be tested

1 PETER 1 V 7.

7That the trial of your faith, being much more precious than of gold that perisheth, though it be tried with fire, might be found unto praise and honour and glory at the appearing of Jesus Christ:

The culmination of our faith is eternal life

1 PETER 1 V 9.

9Receiving the end of your faith, even the salvation of your souls.

COMMENT. It is extremely obvious that faith the size of a mustard seed cannot move mountains, as we have to grow in faith. Rather, faith starts out small and then grows, just as a mustard seed does. We have the promise from God that our faith will grow if we keep all of Gods requirements such as belief etc.