1 John 5:20 - Father is the True God
Last night (8/28/2016), the pastor at an evangelical church read this verse very quickly to the congregation. He said, "incidentally, please note this affirms Jesus is God." I made a note to check when I came home. It says the opposite.
Here is a passage that clearly says the Father is the only true God -- a repeat of John 17:3. Here is what 1 John 5:20 says in the NIV:
We know also that the Son of God has come and has given us understanding, so that we may know him who is true. And we are in him who is true by being in his Son Jesus Christ. He is the true God and eternal life.
The second sentence is key. By saying "we are in him who is true by being in HIS Son Jesus Christ," this clearly implies the one who has a son "is true" and is "the true God." He is both "him" who is true and it is "His" son who is Jesus. Then it says "He is the true God." The HE in the last sentence is not referring to His Son Jesus Christ, but to the true God who has such a Son. The antecedent is not the last preceding word - Christ - but the object of the three preceding object-clauses - "him who is true" -- "in Him "who is true by being "in His son" -- him, him, and his referring to God, the Father, distinct from the son.
The NLT renders the last sentence in part as "he is the only true God." This is virtually verbatim stated in Jesus' prayer to the Father in John 17:3 which helps us connect the dots:
And this is eternal life, that they know you the only true God, and Jesus Christ whom you have sent.
Hence, the pastor relied upon some skewed perception to see 1 John 5:20 as anything different than John 17:3. It is again about the Father -- the "only true God" -- using virtually identical language in 1 John 5:20 as in John 17:3.
For an excellent YouTube discussion how 1 John 5:20 is distorted by Trinitarian assumptions, see this link. This article shows you many examples in the Greek in the NT that you do not use the last antecedent noun to interpret a "He" at the beginning of a sentence.