Hi
How is the Jewish, Christian and Islam religion related?
What are all the same beliefs?
Thanks
My answer will be a bit different than the other posters.
You ask what are the same beliefs, and I will mention some below, as well as some differences, but this is in no way comprehensive. Books can, and have, been written on the differences and similarities.
How are they related?
They all trace their roots back to Abraham and worship the God of Abraham. They are related through Abraham. Judaism came through Isaac and later Christianity came from the Judaic line. Islam came even later, through the line of Ishmael.
What are the same beliefs?
In talking about the similarities, one also must discuss the differences. In many ways, Islam is more similar to Judaism and in other ways it is more like Christianity.
All three religions are monotheistic. Christianity is the only one of the three religions that gives a triune nature to God (although there are non-trinitarian Christians). Judaism and Islam both are adamant in the oneness of God and view trinitarianism similar to polytheism or idol worship. All three religions have various names for God that describe his attributes.
Judaism and Islam both follow a set of laws/ commands put forth by God. Quite a bit of them are alike. There are some differences, for example, in their dietary laws. Both do not eat pork. Both slaughter and prepare foods in similar ways. Kosher foods (in general) are okay for muslims to eat, but there are exceptions. Jews consume alcohol, Muslims do not. Muslims consume shellfish, Jews do not-- but not all Muslims consume shellfish, there are mixed rulings on it. Jews have varying levels of keeping kosher, some much more stringent than others. Christians, are mixed on keeping the laws. There are Christians who believe we are still under the law, and there are those who do not. I would hazard to say that for the most part, Christians in general believe that we are no longer under the law. There are certainly groups of Christians who do keep the laws.
With regards to satan and demons, Islam and Christianity are probably more on the same page, although there are certainly differences also. Judaism, in general, takes a different outlook. About heaven and hell, all three religions have very different opinions. Some sects of Judaism even believe in reincarnation. Christianity and Islam, do not.
Prayer is similar in Judaism and Islam, and different in Christianity. For the most part, Christians do not have prescribed prayers or prayer times; although, there is some prescribed prayers in some Christian circles (reciting the Lord's Prayer for example). Judaism and Islam both have daily congregational prayer times, and also both have prescribed types of prayers. Both also have additional types of prayers (blessings, supplication, etc.) that are associated with various things. The way that one prays is similar in Judaism and Islam (washing, bowing, etc.). Most Christians do not have these same rituals and simply pray in whatever manner they want.
Judaism, in general, has the prophets in the Tanakh (our OT); although, there is some variations, but it is not important here. Judaism also has some female propehts. In Islam there are no female prophets. Christianity accepts that there were some female prophets. Christianity accepts all the prophets of the OT, and also has some in the NT. Islam accept all the prophets in the OT (except women) and also regards Jesus as a prophet and Mohammed as a prophet. Judaism and Christianity do not accept Mohammed as a prophet. There are differences in the religions on things like the nature of the prophets, and also some differences in opinion on who was a prophet.
Judaism does not accept Jesus at all. Christianity, in general, accepts Jesus as the messiah and also as God incarnate. There are some Christians who accept Jesus as Messiah, but not as God incarnate. Islam accepts Jesus as the messiah (although more often you will see it worded as a great prophet), but not as God incarnate. Jews believe Jesus died. Christians believe he died and rose again. Muslims believe he did not die, but was taken to heaven. Christians and Muslims both believe he will come again one day. Jews are still waiting for the Messiah. (In general.)
Jews have the Tanakh as their bible. It, basically, is what the Christians call the OT. Christians have the OT and NT (some Christian Bibles have different books than others). Islam has the Qur'an, and believes in the Torah, gospel, and psalms, but believes they have been changed and are not the original message. There are also differences in beliefs about how the scriptures were given and passed down.
In Judaism, the sabbath is Saturday (sunset Friday to sunset Sat.). In Christianity, for the most part, it is observed on Sunday (although there are Saturday observing groups). In Islam, the holy day is Friday. Observances are very different in each religion (and also vary within each religion).
All three religions promote modesty, but the way it is displayed is different.
I am trying to think of what other major similarities and differences there are to put here.
Within each group you will also find much variations in beliefs. Did you have a specific question?