Dwight L. Moody in his book, The Overcoming Life, states:
"Notice that everything human in this world fails. Every man, the moment he takes his eye off God, has failed. Every man has been a failure at some period of his life. Abraham failed. Moses failed. Elijah failed....
I suppose it was because they were not on the watch. Abraham was noted for his faith, and he failed right there--he denied his wife. Moses was noted for his meekness and humility, and he failed right there--he got angry. ... Elijah was noted for his power in prayer and for his courage, yet he became a coward. He was the boldest man of his day and stood before Ahab and the royal court.... Peter was noted for his boldness, and a little maid scared him nearly out of his wits."
So it is with what John teaches in 1st John that we see whatever is of God is a victor. We all must get our eyes back on Jesus. We must say "I am crucified with Christ, nevertheless I live, yet not I, but Christ lives in me." And "we walk by faith."
And he adds we must be overcomers of the world. Later on he asks, "Are you overcoming the world, or is the world overcoming you?" We must press on.
Whatever you're going through, realize that God is greater.