As you have asked me to elaborate, so I will: the impossibility both for God to lie (ψεύσασθαι) and God's Son to fall from faithfulness (ἀπιστεύειν) is semantically one and the same ontological impossibility (for the ἀδύνατον Hebrews 6:18 has absolutely the same power as the οὐ δύναται of the 2 Tim. 2:13, thus asserting the same degree of steadfastness (μένει) for Jesus as is asserted of God's word in Isaiah 40:8 "the grass withers, the flowers fade, but God's word remains (μένει) forever", in which quote "grass" and "flowers" symbolize the entire created order of reality.

In the above quote, in the term "word" (ῤῆμα) "God's word" is not necessarily to be understood (but quite possible) as His hypostatized Logos, as in John 1:1, but as His inseparable eternal attribute. And the Logos' word has absolutely the same steadfastness as the Fathers word, for as the Incarnate Logos says "the heaven and earth will pass away, but My words will not pass away" (Matt 24:35).

And in the common Kingdom of the Son and the Father, which is established in human hearts the Son remains (μένει) eternally (John 8:35), just as the Father does, for there are no gradations - more and less - in eternity, and, therefore, if the Son remains eternally, so does the Father.

And with them the Holy Spirit, the Spirit of Truth, for it is impossible to be a true worshiper of God but through the Holy Spirit (John 4:23), and only through Whom, the Spirit of Sonship believers are able and invested with authority to become the children of God (Romans 8:15), eternally becoming the temples of Him (1 Cor. 6:19), for the Holy Spirit bears the same stamp of divine ontological impossibility as do the Son and the Father, for it is impossible for anybody who possesses and is guided by the Holy Spirit not to worship and praise Jesus Christ as Lord and God (cf. 1 Cor. 12:3) in likeness of Thomas (John 20:28).

As you have asked me to elaborate, so I will: the impossibility both for God to lie (ψεύσασθαι) and God's Son to fall from faithfulness (ἀπιστεύειν) is semantically one and the same ontological impossibility (for the ἀδύνατον Hebrews 6:18 has absolutely the same power as the οὐ δύναται of the 2 Tim. 2:13, thus asserting the same degree of steadfastness (μένει) for Jesus as is asserted of God's word in Isaiah 40:8 "the grass withers, the flowers fade, but God's word remains (μένει) forever", in which quote "grass" and "flowers" symbolize the entire created order of reality.

In the above quote, in the term "word" (ῤῆμα) "God's word" is not necessarily to be understood (but quite possible) as His hypostatized Logos, as in John 1:1, but as His inseparable eternal attribute. And the Logos' word has absolutely the same steadfastness as the Father's word, for as the Incarnate Logos says "the heaven and earth will pass away, but My words will not pass away" (Matt 24:35).

And in the common Kingdom of the Son and the Father, which is established in human hearts the Son remains (μένει) eternally (John 8:35), just as the Father does, for there are no gradations - more and less - in eternity, and, therefore, if the Son remains eternally, so does the Father.

And with them the Holy Spirit, the Spirit of Truth, for it is impossible to be a true worshiper of God but through the Holy Spirit (John 4:23), and only through Whom, the Spirit of Sonship believers are able and invested with authority to become the children of God (Romans 8:15), eternally becoming the temples of Him (1 Cor. 6:19), for the Holy Spirit bears the same stamp of divine ontological impossibility as do the Son and the Father, for it is impossible for anybody who possesses and is guided by the Holy Spirit not to worship and praise Jesus Christ as Lord and God (cf. 1 Cor. 12:3) in likeness of Thomas (John 20:28).