It's often said that because Judaism, Islam, Mormonism, and Christianity share a common historical heritage in Abraham, then they all worship the same God, right? No, they don't.
While Judaism, Islam, and Christianity are all monotheistic. Mormonism is not. Mormons believe in many gods and that they will become gods themselves. They might worship a version of Jesus, but he's like a bad fiction version, not the Jesus of the Bible.
Christianity and Judaism might share the Old Testament and a common ethic, referring to Judeo-Christian values. But where Christianity and Judaism separate is at Christ. Orthodox Jews do not believe that Jesus is the Messiah, the Son of God, and he had some pretty harsh words for them:
"If God were your Father, you would love me, for I came from God and I am here. I came not of my own accord, but he sent me. Why do you not understand what I say? It is because you cannot bear to hear my word. You are of your father the devil, and your will is to do your father's desires" (John 8:42-45).So if someone does not know Christ, the Son of God, then he is not a worshiper of the true God. This also eliminates Islam since Muslims consider it blasphemy to claim that God has a Son. Jesus is not God, they will say, only a prophet.
"O people of the scripture, do not commit excess in your religion or say about Allah except the truth. The Messiah, Jesus, the son of Mary, was but a messenger of Allah except the truth. The Messiah, Jesus, the son of Mary, was but a messenger of Allah and his word which he directed to Mary and a soul [created at a command] from him. So believe in Allah and his messengers. And do not say, 'Three.' Desist, it is better for you. Indeed, Allah is but one God. Exalted is he above having a son. To him belongs whatever is in the heavens and whatever is on earth. And sufficient is Allah as disposer of affairs." Quran, Sura 4:171
But the Bible says whoever does not have the Son does not have the Father either, and the wrath of God remains on him (John 3:35-36). Jews, Muslims, and Mormons need to hear the gospel. No one gets to God except through Jesus Christ. Only those given to Jesus by the Father worship the true God when we understand the text.