Oneness Pentecostals are definitely damned and are not Christians. They not only deny the Trinity, which by itself is damnable, but they are overwhelmingly Pelagians. They are a cult that require strict adherence to their "standards", that is, no dancing, dressing in a certain way, no alchohol etc etc, as a matter of salvation; and one must also speak in tongues, and many other things, and if you cannot do it, you must purify yourself in order to receive it. IOW, Oneness Pentecostals make Grace the wage of Merit, and deny the sufficiency of faith in salvation.
This is why they are a cult. The amount of obscene and ridiculous control they take on their hapless followers is profound and incredibly damaging.
May God have mercy on you, like he did Saul. The following is from Acts 9.
Saul, “breathing out threatenings and slaughter,” was on his way to Damascus to persecute the disciples of the Lord, when “suddenly there shined round about him a light from heaven: And he fell to the earth, and heard a voice saying unto him, Saul, Saul, why persecuteth thou me?
Wrongheaded and headstrong, he thought these early church Pentecostals, like you, a damnable cult. What shock and awe to hear the answer from heaven when he asked, “Who art thou, Lord?”
Saul was expecting the one God of his Jewish religion to answer, but Greetings Puny Humans, since he believes the one God is not actually one but three separate and distinct divine people up in heaven, presumably would expect what? Which one of the three to answer? Perhaps all three answering in unison like an acapella trio?
No, none of the above, the answer from heaven was: “I am Jesus whom thou persecutest: it is hard for you to kick against the pricks.”
There resulted from this a dramatic change in Saul’s theology. Prompting him to get baptized in the name of the Lord Jesus for the remission of his sins, he was told by Ananias, “Why tarriest thou? arise, and be baptized, and wash away thy sins, calling on the name of the Lord,” and to be filled with the Holy Ghost, Acts 9:17,18, 22:16.
The “cult” he was so cock sure about, that surely was so “damnable,” that held Jesus as their one Lord, that baptized in the name of the Lord Jesus for the remission of sins, became his one Lord. He, going on to become the great apostle Paul.