“Alas! is it not a vain endeavor, to open a grave for a dead man to come out? Who lights a candle for a blind man to see by? To open a door for him to come out of prison who is blind, and lame, and bound, yea dead, is rather to deride his misery than to procure him liberty.” (The Death of Death in the Death of Christ, p.305)
In other words, if Christ Jesus died only to make the salvation of sinners possible (rather than dying to actually save His elect people), no one would ever actually be saved.
What good would it be to preach the gospel to someone who is dead in sin (Ephesians 2:1-3), if God did not grant them new life, and even faith itself, so that they might believe in Christ and be saved (Ephesians 2:4-10)? It would be much like (to use Owen’s analogies above) opening up a grave, so that the corpse might come out; it would be like lighting a candle for a blind man to see; it would be like opening a prison door and bidding a bound man (or even a corpse!) to walk free.
As Owen rightly points out, if anyone is to be saved, God must do more than ‘open a door of salvation to all’ (the position of the Arminians). He must also give new life to the dead and saving faith in Christ to enter into salvation. And so all of the glory goes to God alone for the salvation of His people.