So, there is firstly a question of which god. I can objectively prove something about Orthodox Judaism and even Conservative Judaism right off the bat.
However, it seems the debate over 'I' is a key aspect Con wants to deal with. The topic was instigated by Con, so it would be presumed that the 'I' refers to Con. Nonetheless I want to tackle this by making it moot instead of relevant to the debate.
I am going to be presenting a case to you that no matter who the 'I' refers to, a person doesn't believe in 1 or more gods. Furthermore, if the capital G god is honed in on, I want to specifically explore the rule of Judaism that you'd need to blot out the 'o' in G-d to be truly believing in him.
This and multiple sources agree that at least in Hebrew it's a guaranteed rule that when writing G-d you must not write it in full as that word has itself become a name for the creator Adonai. Where Reform Judaism maybe disagrees is that in English it doesn't matter to them (which is what Christians and many Gentiles have come to agree to).
My point is that off the bat it's increasingly unlikely the writer of the title or whoever 'I' refers to is believing in the Jewish G-d. Furthermore, to believe in the Jewish G-d as Judaism describes him creates fundamental problems when claiming to also believe in the Trinitarian variant of him that almost all mainline Christianity purports.
Belief in Jesus as son of God and Messiah is totally incompatible with a Jewish identity. When a Jew adopts such Christian beliefs, he or she loses most of the privileges of a Jew – including receiving synagogue honors, burial in a Jewish cemetery, and (in many synagogues,) synagogue membership.
Any person, Messianic Jew or Evangelical Christian, who tries to convert Jews on the assumption that Jews are damned to Hell and need saving by the grace of God through Jesus, is showing a complete lack of respect for Judaism as a living, vibrant religion. As such, I believe that no matter how much they may profess to “love Jews,” their deeds are showing a profound hatred of Jews and Judaism.
No matter what an individual Jew might believe about the Messiah, the fact is that according to Jewish Scripture, Jesus could not have been the Messiah. Calling Jesus by the Hebrew name of Yeshua does not change the fact that the Messianic prophecies of the Hebrew Bible have not yet been fulfilled – therefore, the Messiah or the Messianic era has not yet arrived.
You are correct that centuries of Christian persecution and proselytization have created widespread animosity among certain elements of the Jewish community. However, more and more, Jews and Christians (and Muslim, Hindu, Buddhist, etc.) are engaging in mutually respectful dialogue and interfaith worship services on special occasions, such as Thanksgiving. This, as much as anything, may be a sign that a world in which the messianic prophecies of peace is drawing nearer.
- ahavasisraelgr.org
So, you see now a major issue right? Even if we handle only the Judeo-Christian deity that is named capital G to the o to the d, we will find a big issue; you cannot fully believe in one while believing in the other. Christians clearly challenge this. Christianity believe it does believe in the Jewish deity and that all along he was an undercover Trinity which he breadcrumbed with secret clues. The problem is that he also only made a religion for 1 specific ethnicity and that if that same religion did extend to the Goyim/Gentiles it would need to hold with it the rules it had attached such as no pork eating, male circumcision, Saturday and not Sunday as sabbath so on and so forth.
The real issue here is that to fully believe in Judaism's deity is to disbelieve Christianity's. That means even if Christianity does claim it believes in Judaism's deity, it clearly categorically does not since Judaism's deity as defined by Judaism itself completely lacks compatibility with the one of Christianity for multiple reason, the most instantly obvious being Trinity and that Jesus or as he was called 'Yeshua' is not their accepted Messiah.
The only reason I stuck to these 2 religions so far is because I predict that Con will nitpick about capital G in the term 'god' in the title.
Let's look at the definition of this word even as a proper noun.
God : the supreme or ultimate reality: such as
a
: the being perfect in power, wisdom, and goodness who is worshipped (as in Judaism, Christianity, Islam, and Hinduism) as creator and ruler of the universe
b
Christian Science : the incorporeal divine Principle ruling over all as eternal Spirit : infinite Mind
2
or less commonly God : a being or object that is worshipped as having more than natural attributes and powers
specifically : one controlling a particular aspect or part of reality
Greek gods of love and war
merriam-webster
God
noun [ S not after the ]
uk
/ɡɒd/ us
/ɡɑːd/
A2
(in some religions) the being who made the universe and is believed to have an effect on all things:
dictionary.cambridge.org
In both instances, I speficially honed in on the definition(s) that best fit the proper noun capital G term, to avoid either side abusing lowercase common noun definitions.
I want to now explain something about compatibility and problems when we start admitting that even Zeus and the liked of Athena or Odin and the likes of Thor as well as of course Shiva, Visnu so on and so forth are able to be deemed capital G 'god' as per these definitions.
The problem is 2-fold:
- Logically there's no way all coexist, since for instance Zeus has to be apex deity inside that but Odin has to be apex (All-Father) inside that.
- Carrying on from point 1, inside Judaism and Christianity (largely due to its carry-over texts from Judaism) as well as Islam, there are parts of scripture that categorically make it an extreme sin to believe in other deities. Even if you take the loophole in Judaism hyperliteral and say it says 'above' and not 'any other' it still would be impossible to believe in other gods to the extent you'd dub them the capital G god.
I will cite the commandments now and add to it. Judaism and Islam both strongly make clear that not only is belief in this 1 deity mandatory but the penalty for an adherent of it to ever dare advocate otherwise and push for another deity should result in death (Judaism specifically states stoning while Islam is vague), the angle Islam takes is to do with apostacy and misleading others as a Muslims or ex-Muslim.
Let's start with the first 2 Commandments of Judaism (that Christianity also adheres to but differs on which day is the Lord's day in most sects+denominations):
I am the LORD your God; you shall not have strange gods before me.
You shall not take the name of the LORD your God in vain.
hallow.com
I want to expand on the 2nd Commandment. That is a Catholic Christian interpretation just quoted, the Judaic Talmudic one is as follows:
"Thou shalt have no other gods before me. Thou shalt not make unto thee any graven image"
wikipedia.org
What is essential to note is that Greeks, Hindus, Norse so on and so forth literally require you to make graven images.
Let's see it in full:
... any graven image, or any likeness [of any thing] that [is] in heaven above, or that [is] in the earth beneath, or that [is] in the water under earth: Thou shalt not bow down thyself to them, nor serve them.
wikipedia.org
To the Jews this even would deem Jesus himself in a statue form as a graven image, let alone as a painting etc.
Islam is quite similar on all those matters (after all it plagiarised Judaism and Christianity plus Arab Paganism to form a huge amount of its scripture). The main issue here is that Islam is crystal clear on a key thing relevant to the debate:
Shirk (Arabic: شِرْك, lit. 'association') in Islam is a sin often roughly translated as 'idolatry' or 'polytheism', but more accurately meaning 'association [with God]'.[1][2][a] It refers to accepting other divinities or powers alongside God as associates.[4][5] In contrast, Islam teaches that God does not share divine attributes with anyone, as it is disallowed according to the Islamic doctrine of tawhid.[6][7] The Quran, the central religious text of Islam, states in 4:48 that God will not forgive shirk if one dies without repenting of it.[8][7][9]
The one who commits shirk is called a mushrik.[b] The opposite of shirk is tawhid[c] and the opposite of mushrik is muwahhid.[d].
wikipedia.org
The pentalty for either Shirk or apostacy in Islam are a bit ironically different.
If you do Shirk but don't openly say you deny Allah, you cannot be killed for it (but trust me, that happened/happens as you just got/get branded an apostate anyway). It says Shirk is unforgivable though and that Allah basically guarantees you Hell especially if you did it near or while dying and didn't sufficiently repent. Note that repentance in Islam is by works, not just begging but earning so as I said doing shirk and not working the debt off for years may result in the unforgivable nature of it reamining on your soul in the afterlife.
Both religions basically say you will be killed if you break the part mentioned but they frame it as apostacy-oriented.
NOTE THAT I DO NO ADVOCATE AT ALL FOR THE FOLLOWING, DO NOT ADHERE TO IT PLEASE!
Deutoronomy 13
https://quran.com/an-nisa/89-91
It is very obvious to me that you cannot fully believe in that God and another at the same time. What I am getting at, very clearly is that to believe in 1 God guarantees you disbelieve others.