In his one and only epistle, the Apostle James discusses double-mindedness. In Chapter One he shares the symptoms and in Chapter Four he reveals the cure. How does one overcome double-mindedness? See James 4:7.

"Submit to God." Literally this means to stand under. Like a soldier we are to obey our commanding officer Jesus Christ. God's way is the best way.
"Resist the devil." Literally this means to stand against. We must oppose and withstand the advances of the wicked one.

Overcoming double-mindedness involves growing faith and eliminating doubt. Thus, it is important to know who will help us and who will hurt us. God inspires faith and Satan creates doubt. So, stand under God and stand against the devil.