Because these things underlie our very existence, Lehi highlights the necessity to spread the word of it to the inhabitants of the earth. These principles will affect all mankind, whether or not they are cognizant of them. The better they know truth, the better they can learn to accept the atonement of the Savior. Lehi does note that in addition to the redemption from sin, Christ will also effect the redemption from death.
Once again the compact nature of these verses implies that Lehi is reiterating information that they should already know, for he does not go into detailed explanations. He is rather using this information to establish the direction of his general discourse.