[but] during these final days He has spoken to us through His Son [Note: This period refers to the Christian age (See Acts 2:14-36)], whom He appointed to be heir of all things [and] through whom He created the universe. [See John 1:3; Col. 1:16].

For it was fitting that God, for whom and through whom everything exists, in order to lead many [of His] children to glory [i.e., heaven], would make the author [or, pioneer] of their salvation [i.e., Jesus] completely [qualified] through [His] sufferings.