The Jews believe that He was an imposter, posing as Messiah and faking His death and resurrection.   They believe in Him as a historical person.   

The Muslims believe in Jesus as a great prophet of God, but not God`s Son.   

Christians believe what?   Unfortunately, there is not a consensus about Jesus even among the ones who claim to believe in Him according to New Testament scripture.   

Some Christians believe that Jesus is only the Son Of God.   
Some Christians believe that Jesus is God.   

Some Christians believe that Jesus has eliminated all laws and replaced them with Grace.   
Some Christians believe that salvation is by Grace Through Faith only.   
Some Christians believe that salvation is a combination of Grace and works.   

Some Christians believe that the Holy Spirit is the third person of the Godhead.   
Some Christians believe that the Holy Spirit was only for the Apostles of the first century.   
Some Christians believe that the Holy Spirit is the Spirit Of Christ Jesus.   

Some people believe that Jesus is Saviour but that we will stand before God.   
Some people believe that Jesus is Saviour and Righteous Judge of the quick and dead.   

Some people believe that you must be baptized in the name of the Father, Son and Holy Ghost.   
Some people believe that you must be baptized in the name of Jesus.   

So, when we really bear down to think about what it means to believe in Jesus, it is not really very clear.   

Uncertainty breeds doubt.   Error breeds more error.   Truth, however, is incorruptible, powerful and effective.   

True Christianity is believing that Jesus is God - the One and only God.   Any doubts about His status is effectively denial of Him.   Denial of Christ Jesus is deadly.   

True Christianity is believing that we are saved solely and entirely by Grace Through Faith In Christ Jesus as the risen Lord Of Lords, King Of Kings and Saviour.