To illustrate how many Trinitarians interpret 1 Cor. 12:3, I will provide some quotes from biblehub.com. We could multiply such statements, but this way of producing them is most expedient for me. Nevertheless, I agree with Kaz that it seems incredible to assert that no Jew ever questioned the move from monolatry/strict monotheism to the veneration/worship of Christ and the holy spirit.
JFB Bible Commentary: "Lord—acknowledging himself as His servant (Isa 26:13). 'Lord' is the Septuagint translation for the incommunicable Hebrew name Jehovah."
Gill's Exposition of the Entire Bible: "And that no man can say that Jesus is the Lord, but by the Holy Ghost; or Jehovah; which, with the Jews, was a name ineffable, to which the apostle might have respect. Christ is Lord of all, of angels, good and bad; of men, righteous and wicked; of the chief among men, the kings, princes, and lords of the earth; as he is God by right of nature, and as Creator of them by virtue of that; and because of his providential power and influence in the government of the universe; he is Lord of his church and people, by the Father's gift of them to him"
Pulpit Commentary: "No man can say that Jesus is [the] Lord, but by [in] the Holy Ghost. It involved a strong rebuke to the illuminati, who professed a profound spiritual insight, to tell them that no man could make the simple, humble confession of the divinity of Jesus (for 'Lord' is here an equivalent of the Hebrew 'Jehovah') except by the same inspiration as that which they so terribly abused."
Alford's GNT: "So κύρ. Ἰης., Jesus is Lord (all that is implied in κύριος, being here also implied: and we must not forget that it is the LXX verbum solenne for the Heb. Jehovah). By these last words the influence of the Holy Spirit is widened by the Apostle from the supernatural gifts to which perhaps it had been improperly confined, to the faith and confession of every Christian."