"You are of God, little children, and have overcome them because greater is he who is in you than he who is in the world" 1 John 4:4. The "them" referenced here are the false teachers of v.1 who were leading the believers astray. This is not a blanket promise that we will win out over every bad circumstance in life (a false teaching often found today linked to the prosperity gospel), but rather, the assurance that they will not be led astray if they stick together. This is populism at its best - the assurance that elite teachers claiming special knowledge are not match for God's Spirit who is in them collectively (the "you" here is plural).
This statement has been taken out of context and perverted to imply that as an individual, I don't need to be taught; that God's personal revelation is enough, which was the very false teaching John was battling. Any time someone says they have a new revelation, a new teaching that will change our lives, we are wise to be wary. God trusts his people...if we are willing to trust each other enough to listen to one another.
On the other hand, the verb tense is important. It doesn't say, "you WILL overcome," but that "you HAVE [already] overcome," because Christ's Spirit is in us, and he has already overcome the world (John 16:33) through his passion and death. Victory over the world (personified in these false teachers) is a done deal if we stay unified; connected with other believers.
The problem is, we don't always feel like overcomers; if anything, we frequently feel overcome, bowled over, trampled by this world system. So we are faced with a decision: do we trust God's promise or our feelings. I wonder how different our days would be if we started each day rehearsing this Scripture instead of rehearsing the doubts and fears that so often populate our thoughts? We HAVE already overcome! Not will someday overcome; our victory is already secure in Christ; it is for us to believe and live into it. That's worthy of my thanks tonight!