William Scott: “Rather, I would argue that the opposite is the case per the Scriptural commands to never attempt to communicate with those who have passed from this life, whether they are the souls of brothers and sisters who are alive with God (as Abraham and Samuel) or the souls of those eternally separated from God.”
You state that there are “no scriptural prohibitions with regards to the Church”. However, all moral commands in the Old Testament are binding on the Church, as I’m sure you agree. The Old Testament prohibition against communicating with departed souls is therefore binding on the Church. Communicating with the souls of the departed Old Testament saints (all of whom continued to live after death, as Christ makes clear in the Gospel–e.g. Mark 12:27) was clearly included in this Scriptural prohibition.
There is nothing in the New Testament that could reasonably be construed to abrogate this command–certainly not the fact that departed saints, both in the New Covenant era and prior thereto, are alive with God (since this was a reality revealed even in the Old Testament Scriptures).
As noted above, the handful of New Testament passages that are regularly cited as favorable evidence for prayers to departed saints are ambiguous at best and cannot be deemed to carry the weight of a practice that is in prima facie conflict with Scriptural commands and that lacks a single real example in the Old or New Testament Scriptures, the Deuterocanonical books, or in any work of the Church Fathers for the first 300 years or more of the Church.