I think of myself as a Catholic with a strong Unitarian bent.
To me, one of the central portions of my faith is belief in the Holy Spirit, which we recognize from the Niceno–Constantinopolitan Creed:
"I believe... in the Holy Ghost, the Lord and Giver of life, who proceedeth from the Father, who with the Father and the Son together is worshiped and glorified, who spake by the prophets."
I don't necessarily think other faiths are unholy or evil. In fact, there's so much truth in other faiths that, like many Unitarians, I tend to believe they too are touched by the Holy Spirit.
In Blake's "All Religions are One," I feel he explores this Unitarian idea. To me, his "Poetic Genius" is the same creature - or born of the same creature - as the Holy Spirit.
All Religions are One
by William Blake
The Voice of one crying in the Wilderness
As the true method of knowledge is experiment the true faculty of knowing must be the faculty which experiences. This faculty I treat of.
That the Poetic Genius is the true Man. and that the body or outward form of Man is derived from the Poetic Genius. Likewise that the forms of all things are derived from their Genius. which by the Ancients was call'd an Angel & Spirit & Demon.
As all men are alike in outward form, So (and with the same infinite variety) all are alike in the Poetic
No man can think write or speak from his heart, but he must intend truth. Thus all sects of Philosophy are from the Poetic Genius adapted to the weaknesses of every individual
As none by traveling over known lands can find out the unknown. So from already acquired knowledge Man could not acquire more. Therefore an universal Poetic Genius exists
The Religions of all Nations are derived from each Nations different reception of the Poetic Genius which is every where call'd the Spirit of Prophecy.
The Jewish & Christian Testaments are An original derivation from the Poetic Genius. this is necessary from the confined nature of bodily sensation
As all men are alike (tho' infinitely various) So all Religions & as all similars have one source
The true Man is the source he being the Poetic Genius