The main moral of 1 Samuel 18 is about the power of authentic friendship and the dangers of jealousy and pride. It also highlights the importance of humility and recognizing God's favor, even when faced with adversity. In essence, 1 Samuel 18 teaches us that true friendship is a powerful force, while jealousy and pride can be destructive. It also encourages us to be humble, trust in God's favor, and persevere through adversity with faith and resilience.