In the book of Genesis, it is implied that Adam (and those after him) faced ultimate/permanent death if and only if they transgressed one or more of God's commandments (i.e. sinned).
The Old Testament both explicitly and implicitly teaches that God plans on raising all his righteous remnant (Israel) to eternal life. (By contrast, the evil are at best raised up for judgment and second death.)
See full article to discuss 7 examples:
This is relevant because God’s people are the sinless; they were those who freely submitted their lives to God (via obedience, animal sacrifices etc.). Even if failing at times (“akrasia”), as the highest cognitive level they made the ultimate decision summit to God’s will for their lives—which is to be perfect. This in turn is relevant because such people will truly be made perfect, and this uniquely predicts a general resurrection only if one’s sinlessness predicts one’s resurrection.
Jesus proclaimed to humanity that ultimate death is just for sinners (the sinless won’t stay dead).
This page analyzes four evidences and their relevance:
Biblically, God would uniquely raise the sinless (i.e. ultimately destroy the wicked and preserve the righteous).
This is relevant because the biblical report is reliable here.