I agree with you completely. Believe me, I agree.....
Maybe you've answered this, on a different note.
Why don't you take the consideration of the people who follow the religion and their interpretations of scripture (Buddhist, Jewish, Christian, Muslim, etc) and ask them how they see one truth rather than Bahaullah?
We know how they see their truth or truths and we see it the same way they do even believe more strongly than they do. Here's an example of what we say about Christ and Christianity.
"“As to the position of Christianity, let it be stated without any hesitation or equivocation that its divine origin is unconditionally acknowledged, that the Sonship and Divinity of Jesus Christ are fearlessly asserted, that the divine inspiration of the Gospel is fully recognized, that the reality of the mystery of the Immaculacy of the Virgin Mary is confessed, and the primacy of Peter, the Prince of the Apostles, is upheld and defended."'(Shoghi Effendi)