Praise be to Allaah.
All the religions in their true original state talks abour oness of God, which is Allah and that there's no one but Allah whom one should pray for. This basic concept of Monotheism was preached by ALL messengers that were sent by Allah - be it Hazrat Essa (which led to chritianity), or Hazrat Uzair (which led to Jews) or Prophet Mohammad (May Allah showers His blessings and peace on him) which led to Islam.
Hence, there is ONLY one religion (correct translation of which could be DEEN) and that is ISLAM.
Allaah says (interpretation of the meaning):
“So set you (O Muhammad) your face towards the religion (of pure Islamic Monotheism) Haneef (worship none but Allaah Alone). Allaah’s Fitrah (i.e. Allaah’s Islamic Monotheism) with which He has created mankind. No change let there be in Khalq‑illaah (i.e. the religion of Allaah Islamic Monotheism), that is the straight religion, but most of men know not” [al-Room 30:30]
It was narrated from Abu Hurayrah (may Allaah be pleased with him) that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Every child is born in a state of fitrah (the natural state of man, i.e., Islam), then his parents make him into a Jew or a Christian or a Magian.” (Agreed upon).
The correct view is that what is meant by fitrah is the religion of Islam, as stated in the hadeeth narrated by Muslim from the Messenger of Allaah (peace and blessings of Allaah be upon him), who said: “Allaah said: ‘I created My slaves as haneefs (believers in pure monotheism), then the Shaytaan misled them from their religion; he forbade them what I had permitted to them and commanded them to associate others with Me for which I had not sent down any authority.’”
What it means when it is said that a child is born as a Muslim is that he is born inherently ready, when he reaches the age of discretion, if he is given the choice between Islam and its opposite, to prefer Islam over its opposite and to choose Islam as his religion, so long as there is nothing to prevent him from doing so, such as his whims and desires or tribalism.
Following his desires makes him prefer falsehood so that he may attain some share of leadership or wealth, and tribalism or racial pride makes him follow his forefathers or elders, even if they are not following true guidance.
Hope this answers the question
And Allah knows the best