Lately there have been repeated attempts to make John 10:30 a 'trinitarian' proof text.
Each time the effort has failed.
The text simply doesn't support the trinity at all.
It merely states Jesus and his God are "one".
It doesn't state how.
Nor does the context.
We are left to find other Scriptures that explain "how" Jesus and his God are "one".
The CLASSIC text for this topic is;
John 17:18-23 As Thou hast sent me into the world, even so have I also sent them into the world.
19 And for their sakes I sanctify myself, that they also might be sanctified through the truth.
20 Neither pray I for these alone, but for them also which shall believe on me through their word;
21 That they all may be one; as Thou, Father, art in me, and I in Thee, that they also may be one in us: that the world may believe that Thou hast sent me.
22 And the glory which Thou gavest me I have given them; that they may be one, even as we are one:
23 I in them, and Thou in me, that they may be made perfect in one; and that the world may know that Thou hast sent me, and hast loved them, as Thou hast loved me.
In this text we prove two VERY important things;
1) The believers are "ONE", JUST LIKE Jesus and his God are "one"!
2) It is God's words (LOGOS), that creates this unity!
So, when Jesus states in John 10:30, "I and my Father are one", we KNOW exactly HOW they are one;
John 12:49-50 For I have not spoken of myself; but the Father which sent me, He gave me a commandment, what I should say, and what I should speak. 50 And I know that His commandment is life everlasting: whatsoever I speak therefore, even as the Father said unto me, so I speak.
So, now that we are clear on John 10:30, please don't continue to misuse the text!