In Job 1:6, we read the following:
Now there was a day when the sons of God came to present themselves before the Lord, and Satan came also among them.
In this text, Satan is presented as being among the “Sons of God” (בני האלהים) This can be seen in the verb יצב (to take [their] stand/position”) and that Satan is said to be in their “midst,” that is, he belongs among their ranks, clearly demonstrating that the theology of Job holds to a “Satan” who has real, ontological existence, in contradistinction to some Christadelphian interpretation of the "Satan" texts in Job. When one examines the phrase, “among them” (KJV), one finds that the Hebrew is a phrase consisting of the prefixed preposition (בְּ) meaning “in/among” and (תָּוֶךְ). When one examines the other instances of this phrase in the Hebrew Bible, it denotes someone being a member of a group, not independent thereof (e.g., Exo 28:33; Lev 17:8, 10, 13; Num 1:47; 5:3; 15:26, 29, etc.); indeed, commentators such as David J.A. Clines states that the phrase regularly denotes membership of the group in question (See Clines, Job 1-20 [Word Biblical Commentary, 1989], 19). The bare term תָּוֶךְ also denotes membership, not independence, of the group in question (cf. Gen 23:10; 40:20; 2 Kgs 4:13).
Furthermore, the "Satan" in Job 1:6, in Hebrew, is not just the bare term (שָׂטָן), meaning an "adversary," which, in and of itself, can denote anyone who opposes another, whether divine or not (e.g., the angel of the Lord is referred to as an adversary or שָׂטָן in Num 22:22), but is coupled with the definite article (השטן), “the satan,” which denotes the supernatural tempter (cf. Zech 3:2); one should compare this with similar Greek locutions in the LXX and NT such as such as ο σατανας (Sirach 21:27; Matt 12:26; Mark 3:26; 4:15; Luke 10:18; 11:18; 13:16; 22:31; John 13:27; Acts 5:3; 26:18; Rom 16:20; 1 cor 5:5; 7:5; 2 Cor 2:11; 11:14; 1 Thess 2:18; 2 Thess 2:9; 1 Tim 1:20; 5:15; Rev 2:9, 13, 24; 3:9; 12:9; 20:2, 7); ο διαβολος (Matt 4:1,5,8,11; 13:39; 25:41; Luke 4:2,3,6,13; 8:12; John 8:44; 13:2; Acts 10:38; Eph 4:27; 6:11; 1 Tim 3:6, 7; 2 Tim 2:26; Heb 2:14; James 4:7; 1 John 3:8, 10; Jude 1:9; Rev 2:10; 12:12; 20:10) and ο πειραζω (Matt 4:3; 1 Thess 3:5), all denoting the external, supernatural tempter in most of Christian theologies (some small groups denying a supernatural Satan notwithstanding).
Why is this significant? One popular charge is that Latter-day Saints believe that Jesus and Satan are “brothers.” Left on its own, it is shocking and seen as blasphemous. However, leaving this on its own, with no explanation, is “yellow journalism.”
In Latter-day Saint Christology Christ has existed for all eternity; many critics claim that LDS theology is reflective of Arianism or some other Christology, but that is a non sequitur. D&C 93:21 and other texts affirm that Christ has existed eternally. Notice the “high Christology” of the following two passages from uniquely LDS scriptural texts (more could be reproduced):
And Amulek said unto him: Yea, he [Christ] is the very Eternal Father of heaven and of earth, and all things which in them are; he is the beginning and the end, the first and the last. (Alma 11:39)
I am Alpha and Omega, Christ the Lord, yea, even I am he, the beginning and the end, the Redeemer of the world. (D&C 19:1)
In LDS theology, properly stated (and not the caricature one finds in works such as The God Makers and other presentations thereof) states we all pre-existed as the spirit sons and daughters of God. In that sense, we are all brothers/sisters of Jesus. However, Job 1:6 proves, unless one is a Christadelphian or some other similar group, “the Satan” is one of the “sons of God,” that is, a member of the heavenly court, one of whom was Yahweh. Note Deut 32:7-9 from the NRSV, reflecting the Qumran reading (see this blog post reproducing what a recent scholarly commentary has to say about this important pericope):
Remember the days of old, consider the years long past; ask your father, and he will inform you; your elders, and they will tell you. When the Most High apportioned the nations, when he divided humankind, he fixed the boundaries of the peoples according to the number of the gods; the Lord's own portion was his people, Jacob his allotted share.
While much more could be said, it should be noted that, as with so many beliefs, it is Latter-day Saint theology, not Evangelical theology, that is supported by biblical exegesis.