John 4

22You worship what you do not know; we worship what we know, for salvation is from the Jews. 23But the hour is coming, and is now here, when the TRUE worshipers will worship the Father in spirit and truth, for the Father is seeking such people to worship him. 24God is spirit, and those who worship him must worship in spirit and truth.”

1 John 5:20

20And we know 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, in his Son Jesus Christ. He is the TRUE God and eternal life.

aléthinos- TRUE

alēthinós (an adjective, derived from the other adjective of the same root/alēth-, 227 /alēthḗs, "true to fact") – properly, true (real), emphasizing the organic connection (authentic unity) between what is true (228 /alēthinós) and its source or origin (note the -inos suffix). See 225 (alētheia).

228 /alēthinós ("substantially true") refers to what is essentially true – connecting (visible) fact to its underlying reality. 228 (alēthinós) then emphasizes the integrity of what is true, down to its inner make-up (reality, "true inside and out").

G. E. Ladd, "The Johannine use of 228 (alēthinós) sometimes carries something of the Greek meaning of 'real,' but it is the real because it is the full revelation of God's faithfulness" (The Pattern of New Testament Truth, 81).