Alma ties together all of his threads here. The atonement is provided, and all who desire to partake of it may. However, this is still a point of agency, and some may not chose to take advantage of the atonement. For both, in the “last day” or the day of judgment, that judgment will restore good for good, evil for evil.
Literary: Alma uses a particular phrase: “partake of the waters of life.” The reference to this could either be the association between water and the Tree of Life in the Garden, or to Lehi’s vision of the Tree of Life with is also associated with “living” waters (see 1 Nephi 11:25).
Alma has previously used the expression of “waters of life” and he clearly links it to the concept of the Tree of Life:
Alma 5:33-34
33 Behold, he sendeth an invitation unto all men, for the arms of mercy are extended towards them, and he saith: Repent, and I will receive you.
34 Yea, he saith: Come unto me and ye shall partake of the fruit of the tree of life; yea, ye shall eat and drink of the bread and the waters of life freely;
Since both the Tree in Genesis and the Tree in Lehi’s dream have associations with waters, we cannot be certain which (if we indeed had to chose) was the precedent for this imagery. Certainly the context of Alma’s discourse suggests that the Garden setting is present on his mind, and the use of the “waters of life” here is certainly occasioned by the connection to the events of the Fall that he has been discussing.