Alma 46:9

Yea, and we also see the great wickedness one very wicked man can cause to take place among the children of men.

One wicked man gains power only when we give it to him.  This we learn from history. When we become complacent and turn over responsibility for our lives to someone else, we abrogate our agency. The only person we can trust with our agency is God. Everyone else will misuse it for their own gain. Thus, the way to stop a wicked person from getting control is to refuse to give it to him, be it political, financial, emotional or spiritual.

Alma 30:18

And thus he did preach unto them, leading away the hearts of many, causing them to lift up their heads in their wickedness, yea, leading away many women, and also men, to commit whoredoms—telling them that when a man was dead, that was the end thereof.

Satan's great ploy is to convince us that absolute truth and eternal right and wrong do not exist. If he can get us to doubt that God cares about what we do, our own imaginations will lead us down any number of paths, none of which will be right. God has given us a conscience, but if we sear it with a hot iron, we can destroy guilt. We then become laws unto ourselves. Chaos reigns, anarchy follows, and misery is always the results, both for the individual and for society. I testify that God is real, he knows us, and he cares about us. Death is not the end but only a step closer to him.

Alma 11:24

Believest thou that there is no God? I say unto you, Nay, thou knowest that there is a God, but thou lovest that lucre more than him.

Knowing God lives and loving him are two different things. The definition of wickedness is knowing about God but acting against his will, knowing about the things of God but loving the things of the world more, knowing God's power but trusting in worldly power instead. Why would we settle for worldliness when we can have godliness?