The One True G-d compared with the Triune G-d

Some people believe Christians worship 3 gods . True believers worship One G-d in Three Persons. This is found in Deuteronomy 6:4 where the word " One" used for G-d is a compound unity.  "Here, O Israel: The L-RD our G-d is one L-RD."   Isaiah 48:16and 17 shows the One True G-d in three persons the L-rd G-d, his Spirit, and me(the L-RD).  "Come ye near unto me, hear ye this; I have not spoken in secret from the beginning; from the time that it was, there am I; and now the L-rd G-d, and his Spirit, hath sent me.  Thus saith the L-RD, thy Redeemer, the Holy One of Israel; I am the L-RD thy G-d which teacheth thee to profit, which leadeth thee by the way that thou shouldest go."  The "me" speaking is the Redeemer, The Holy One of Israel, The Messiah, G-d himself.

So you see, the Trinity was not started with the Christian believer but was from the beginning of Scriptures, in the Tenach . It is the same doctrine taught today in the New Covenant.