Book of Mormon, First Nephi 1:14

And it came to pass that when my father had read and seen many great and marvelous things, he did exclaim many things unto the Lord; such as: Great and marvelous are thy works, O Lord God Almighty! Thy throne is high in the heavens, and thy power, and goodness, and mercy are over all the inhabitants of the earth; and, because thou art merciful, thou wilt not suffer those who come unto thee that they shall perish!

God's power is over every person on earth. No one is beyond His reach or outside the pale of His influence. Though many may ignore Him, deny Him, or even fight against Him, they never overcome Him. They can do nothing that He does not permit them to do. Pilate claimed the power to crucify Jesus, but the Master taught him the truth, that the only power he had was power permitted him by God to fulfill the plan of the atonement.

We can have faith that God uses His power to benefit us in goodness and mercy. His very nature is goodness and mercy. Unlike the inconsistent nature of mortal man, God's nature is consistent and unchanging. He does not have to fight against the natural man. Therefore, all that He does is good and merciful. He cannot be any other way. We can therefore trust that every use of His power is a demonstration of His goodness and mercy.

Our finite minds may not comprehend how some of His actions are for our good and extend mercy to us. Of course, not everything that happens in our lives is initiated by God. He has granted us agency and sufficient power to exercise that agency meaningfully. Many choose to exercise their agency in ways that harm others, either accidentally or intentionally. We often suffer because of the agency of others or even because of our own poor use of agency. Because God is good, He lets us have agency, but because He is merciful, he has provided a Savior for us, whose atonement will heal all the damage done by sin and stupidity.

His power is over all, and so is His goodness and mercy. No one will miss out on any glorious blessing that he is willing to receive because God lacks the power to grant that blessing. If we miss blessings, it will be only because we choose to turn our backs on those blessings, but not because God cannot grant them.