Bible as standard for this thread please.
Id like us to consider if this is "sin".
IF sin, how to remedy?
But there is the problem.
It is precisely because scripture is not sufficient that denominations proliferate holding opposing doctrines in every aspect of belief - they interpret scripture differently.
Scripture cannot solve its own limitations, but if you ask scripture to validate its own limitations leading to the denominational problem ( " as many doctrines as heads" lamented Luther)
I choose
1/ the fact that nowhere does scripture say "scripture alone " without which sola scriptura is a logically self defeating proposition.
2/ it says " the pillar and foundation of truth is the church" so identifying truth outside it and the apostles and successors given the power to " bind and loose" on doctrine - so highlighting that finding the "true church" matters
3/Our lords promise that his " church would be one" ( noting that the church is stated as the " household of a god" so a physical manifestation , not just a spiritual association, and that the " gates of hell would not prevail"
So look for a church whose doctrine is essentially unchanged in millennia.
4/" how can they teach if they are not sent? " the succession matters to knowing which have true teaching,
Clearly promoting false doctrine is sin
Denominations proliferate and split because of doctrinal differences, The solution to resolve the doctrinal so denominatiomal problem is studying early church tradition and authority.