If faith is all you need in Jesus why does Jesus state he that disobeys the son of man doesn’t have life? John 3:36?

As you quoted: Jesus tells us 'Faith and Obedience' are need for salvation.

(John 3:36) “the one who disobeys the Son will not see life, but the wrath of God remains upon him.”

And Paul agrees:

(2 Thessalonians 1:7, 8) “But you who suffer tribulation will be given relief along with us at the revelation of the Lord Jesus from heaven with his powerful angels 8 in a flaming fire, as he brings vengeance on those who do not know God and those who do not obey the good news about our Lord Jesus.”

Paul also tells us 'Faith and Love' are needed for salvation.

(1 Corinthians 13:2) “. . .and if I have all the faith so as to move mountains, but do not have love, I am nothing.”

Jesus tells us 'if we don't endure to the end, we aren't saved.

(Matthew 10:22) “22 And you will be hated by all people on account of my name, but the one who has endured to the end will be saved.”

Jesus tells us if we don't forget others, we aren't saved.

(Matthew 6:14, 15) “14 “For if you forgive men their trespasses, your heavenly Father will also forgive you; 15 whereas if you do not forgive men their trespasses, neither will your Father forgive your trespasses.”

Jesus tells us our judgment is based upon our 'deeds' or 'works'

(Revelation 3:1) “. . .‘I know your deeds, that you have the name that you are alive, but you are dead. . .”

(Revelation 3:15, 16) “15 ‘I know your deeds, that you are neither cold nor hot. I wish you were cold or else hot. 16 So because you are lukewarm and neither hot nor cold, I am going to vomit you out of my mouth.”

The road leading to everlasting life is narrow and cramp and not broad and spacious.

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Jesus definitely teaches that he shall reward us according to our works, not our beliefs.  Faith without works is dead, and so are we.

John 3:36 doesn't say that.  Here is what it says:

John 3:36 He that believeth on the Son hath everlasting life: and he that believeth not the Son shall not see life; but the wrath of God abideth on him.

So you are wrong.  It is about believing in Jesus.  Not about works. So Romans 4:5 proves you wrong as well.  Here is the truth:  Death leads to immediate heaven or hell, and it is too late to be saved, after death.  To be in heaven and not hell, believe in the Lord Jesus Christ, who is God and who died on the cross and shed His blood to pay for all of our sins in full, and who was buried, and who resurrected from the dead.  The only way to avoid hell is by believing in the Lord Jesus Christ, without adding any of your own works.  See Romans 4:5, 1 Corinthians 15:3-4, and John 3:16.

And Mt. 7:21 too.

The problem is that even the devil believes in Jesus Christ. 

"DEAD spirits" (Romans 5:12-14; I Corinthians 15:21-22)

"...know nothing at all" (Ecclesiastes 9:5).

"Faith" is "afterwards revealed" (Galatians 3:23) 

After one has been "QUICKENED back to life" (Ephesians 2:1) 

From their "DEAD spirit."

By His (((POWER))) that comes upon us" (Acts 1:8) after Holy Spirit baptism (Acts 1:5)

As a "Spiritual gift" received (I Corinthians 12:9) after Holy Spirit baptism (I Corinthians 12:13)

That "GOD deals in measure" (Romans 12:3).

For "Jesus is the author and finisher of our faith" (Hebrews 12:2).

So, who says you only need faith?

According to the bible, Jesus had many teachings.

Most about loving others.

I'm an atheist and I never heard a Christian say you only need faith.

According to the bible, Jesus did say to avoid false prophets, and doomsday death cults like the jehovah's witnesses.