score:6
I don't see why this should be complicated. Soteriology is the study of salvation (Greek σωτηρία). Succinctly stated, Arianism posits that the Lord Jesus Christ is not "the only true god" (ὁ μόνος ἀληθινὸς θεός; cp. John 17:3), Yahveh (cp. Isa. 44:6), but rather, a creation of the one true god (i.e., a creature).
According to Isa. 43:11 (cp. Isa. 45:21; Hos. 13:4), it is written,
I, [even] I, am Yavheh, and there is no savior besides Me.
אָנֹכִי אָנֹכִי יַהְוֶה וְאֵין מִבַּלְעָדַי מוֹשִׁיעַ
If the Lord Jesus Christ is not Yavheh, then he cannot effect salvation for humanity, for Yavheh Himself states, "There is no savior besides Me."
Some may suppose that salvation is ultimately effected by Yahveh via the proxy of the Lord Jesus Christ.
However, this is refuted by Psa. 49, in which it is written,
7 A man certainly shall not redeem his brother, nor give his ransom to God.
7 אָח לֹא־פָדֹה יִפְדֶּה אִישׁ לֹא־יִתֵּן לֵאלֹהִים כָּפְרוֹ
15 But God shall redeem my soul from the power of the grave, for He shall receive me. Selah.
15 אַךְ־אֱלֹהִים יִפְדֶּה נַפְשִׁי מִיַּד־שְׁאֹול כִּי יִקָּחֵנִי סֶֽלָה
When it comes to the redemption of a man's soul from the power of the grave, man cannot redeem his brother. Only God can. Therefore, the Lord Jesus Christ cannot be just a man, otherwise he is wholly incapable of effecting the redemption of humanity. Consequently, if the Lord Jesus Christ is not God, then he cannot be the savior or redeemer of humanity.