Our problem:
1.     Unbelief

Exodus 14:14-15, The LORD shall fight for you, and ye shall hold your peace. And the LORD said unto Moses, Wherefore criest thou unto me? speak unto the children of Israel, that they go forward:

Revelation 21:8, But the fearful, and unbelieving...shall have their part in the lake which burneth with fire and brimstone: which is the second death."

1 Corinthians 4:17, For our light affliction, which is but for a moment, worketh for us a far more exceeding [and] eternal weight of glory; 

John 14:1-3, Let not your heart be troubled: ye believe in God, believe also in me.  In my Father's house are many mansions: if [it were] not [so], I would have told you. I go to prepare a place for you.  And if I go and prepare a place for you, I will come again, and receive you unto myself; that where I am, [there] ye may be also. 

Hebrews 3:19, So we see that they could not enter in because of unbelief.

2.     Murmuring and complaining
Unbelief leads to murmuring and complaining.

a.  Temporal needs:

Hebrews 13:5, [Let your] conversation [be] without covetousness; [and be] content with such things as ye have: for he hath said, I will never leave thee, nor forsake thee.

Peter 5:7, Casting all your care upon him; for he careth for you.

b.     Appetite

Jeremiah 6:16, Thus saith the LORD, Stand ye in the ways, and see, and ask for the old paths, where [is] the good way, and walk therein, and ye shall find rest for your souls.

Genesis  1:29, And God said, Behold, I have given you every herb bearing seed, which [is] upon the face of all the earth, and every tree, in the which [is] the fruit of a tree yielding seed; to you it shall be for meat.

c.     Church Leadership

1 Chronicles 16:22, [Saying], Touch not mine anointed, and do my prophets no harm.

Ephesians 5:23, For the husband is the head of the wife, even as Christ is the head of the church: and he is the saviour of the body.

3.     Idolatry

1 Samuel 15:23,   For rebellion [is as] the sin of witchcraft, and stubbornness [is as] iniquity and idolatry.

Deuteronomy 6:5, And thou shalt love the LORD thy God with all thine heart, and with all thy soul, and with all thy might.

Our desert life today:

Isaiah 35:3, Strengthen ye the weak hands, and confirm the feeble knees.

1 Thessalonians  5:14, Now we exhort you, brethren, warn them that are unruly, comfort the feebleminded, support the weak, be patient toward all [men].

Romans 15:1, We then that are strong ought to bear the infirmities of the weak, and not to please ourselves.

Romans 6:16, Know ye not, that to whom ye yield yourselves servants to obey, his servants ye are to whom ye obey; whether of sin unto death,or of obedience unto righteousnes?  

Ephesians 6:12, For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high [places].

1 Peter 5:8, Be sober, be vigilant; because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour:

Matthew 26:41, Watch and pray, that ye enter not into temptation: the spirit indeed [is] willing, but the flesh [is] weak.

Numbers 14:26-31, And the LORD spake unto Moses and unto Aaron, saying,  How long [shall I bear with] this evil congregation, which murmur against me? I have heard the murmurings of the children of Israel, which they murmur against me. Say unto them, [As truly as] I live, saith the LORD, as ye have spoken in mine ears, so will I do to you:  Your carcases shall fall in this wilderness; and all that were numbered of you, according to your whole number, from twenty years old and upward, which have murmured against me,  Doubtless ye shall not come into the land, [concerning] which I sware to make you dwell therein, save Caleb the son of Jephunneh, and Joshua the son of Nun.  But your little ones, which ye said should be a prey, them will I bring in, and they shall know the land which ye have despised. 

Matthew 18:15-17, Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother. But if he will not hear [thee, then] take with thee one or two more, that in the mouth of two or three witnesses every word may be established. And if he shall neglect to hear them, tell [it] unto the church: but if he neglect to hear the church, let him be unto thee as a heathen man and a publican.

Romans 9:27, ...Though the number of the children of Israel be as the sand of the sea, a remnant shall be saved.