You laud the similarities of the various ancient texts, but ignore the differences. If you watch the video I linked above, it talks about how the Johannine Comma was inserted through force, and was not in the original Greek texts. Other than those few verses (John 5:7-8), the entire concept of the Trinity has extremely weak support within the book we have. It does have support in Mithraism (the religion of Constantine and many other notable people of the period and region), but is completely absent in the teachings of Jesus. Without that verse, which substantial evidence suggests was inserted after the fact, it wouldn’t have a leg to stand on. Indeed, it wasn’t even a part of the doctrine until 383 AD. So yes, it was very much a “gradual” thing. I agree completely. Just because I name explicitly the 325AD event as momentous doesn’t mean I think there was nothing else that went on. What’s important is looking at the connections between events. When you look at the connections, and what was purposefully left out and/or silenced, the “organicness” of it comes into question.

A lot to unpack here but I’ll address each assertion you make:

1. Johannine Comma: This refers to a disputed passage in 1 John 5:7-8 regarding the Trinity. While some manuscripts include this passage, many critical editions, including modern translations, omit it due to limited manuscript support. However, the absence of this specific passage doesn't negate the broader concept of the Trinity, which is supported by various other verses in the New Testament (e.g., Matthew 28:19; 2 Corinthians 13:14).

2. Support for the Trinity: While the term "Trinity" isn't explicitly used in the Bible, the concept is reflected in verses portraying Father, Son (Jesus), and Holy Spirit as distinct yet unified (e.g., John 14:16-17, 26; Matthew 28:19). Early Christian writers, such as Ignatius of Antioch and Justin Martyr, also alluded to this triune understanding.

3. Mithraism Influence: The assertion that the Trinity concept derives from Mithraism is debated among scholars (I know this statement will trigger you). While Mithraism and Christianity existed concurrently, drawing direct lines of influence is challenging. The development of Christian doctrine involves complex theological discussions and debates within the early Christian community.

4. Council of Constantinople (381 AD): The explicit declaration of the Nicene Creed, including the affirmation of the Trinity, took place during the Council of Constantinople in 381 AD. This event solidified and clarified theological language but doesn't imply a sudden introduction of the concept. The discussions on Christ's divinity and the nature of God had been ongoing since earlier councils.

While specific verses or terms may not be universally present, the theological groundwork for the Trinity is discernible in various parts of the New Testament and evolved through early Christian theological deliberations. The intricacies of these developments require nuanced exploration within their historical and theological contexts.