Most importantly, we need to bear in mind that Jesus and his disciples were all Jews. Christianity is like the FULFILMENT of the Old Testament hopes. It's like the Christian software program has 3 diskettes to install:

a) 1st disk is 'Old Testament',

b) 2nd disk is 'Jesus'

c) 3rd disk is 'The Church'.

This ENTIRE PROGRAM is called 'The Plan of God for His True People'.

Now, the Jews ALSO want to install the whole program, and they AGREE with Christians that the 1st disk is necessary. But they do not believe that Jesus represents the 2nd disk.

So right now, Jews are still waiting for the 2nd Disk. Christians are CURRENTLY INSTALLING the 3rd disk, and waiting for the 4th Disk, "The Return of Jesus Christ"!

Therefore, "Christians" - in one sense - are those who believe that the program needs all 4 diskettes. Anyone who does not think so - including this race of people called the Jews - would not be called "Christian".

But(!!), as mentioned at the start, the disciples themselves were JEWS! So there are TWO groups here: Jews who believe in Christ (Christian Jews) and Jews who don't (non-C Jews)

Wrapping this up:

1. Are Jews Christians? Some are, some are not.

2. Do they follow strict Jewish customs only and not believe in Jesus? These would represent the non-Christian Jews.

On to a related question:

Generally, because :

• Jesus didn't 'fit' their understanding of what a Messiah would look like. Many Jews expected Jesus to defeat the Roman empire, kick out those jokers presently controlling the Temple and to RUN IT PROPERLY, and to create a restored and powerful nation of Israel (a bit like today, isn't it?).
• Jesus message of a dying Messiah was impossible for some to believe; they thought that a CRUCIFIED Messiah was a defeated Messiah. Somehow the idea that God was fighting a DIFFERENT ENEMY than Rome, and that His victory comes not by power but by love and sacrifice, wasn't very appealing.

• The main Jewish political parties (e.g. the Pharisees, the Sadducees, High Priests - they either ruled the Temple or had a huge influence on the common people) were blinded (or 'hardened') by their pursuit of power/greed, and Jesus represented a direct challenge to their power (e.g. the Temple-cleansing incident).

The issues are certainly a lot more complicated than what I've outlined above, but still…

Hope this helps,

Alwyn