Trinitarianism while not a denomination, is a theological doctrine rooted in philosophical reasoning agreed across almost all mainstream churches. Oneness is another theological framework based on Modalism, so again, not a denomination. Unitarianism is a theological framework rejecting the Trinity, affirming the oneness of God as the Father alone. Pentecostalism is a historical introduction of doctrines about receiving the Holy Spirit, speaking in tongues, and the laying on of hands for receiving the Holy Spirit, so again, not really a denomination, more a movement. The truth is, there are Pentecostal missionaries, elders or the like, who when they lay hands on believers, those believers do visibly receive the Holy Spirit as shown by typical manifestations such as prophesying, speaking in tongues, working miracles, and this is irrespective of whether they believe in the Trinity dogma, or not. Yet almost all Pentecostal churches insist on either belief in Trinity dogma or belief in Oneness theology, with hardly any exceptions. I find that sad. Theologies such as Unitarianism, while having many virtues, may overlook the Pentecostal understanding of the Holy Spirit, as they do not recognize the Spirit as a distinct person separate from the Father. Maybe they simply need to learn this truth too, like the Pentecostals who have received this Holy Spirit.
