The battle is the Lord’s

“47 Then all this assembly shall know that the Lord does not save with sword and spear; for the battle is the Lord’s, and He will give you into our hands.”
1 Samuel 17:47 (NKJV)

David was already the anointed King of Israel, but most people (including King Saul and Goliath) were unaware of this. In essence, King Saul (who should have gone out and defeated Goliath) gave the job to his successor without realizing it. All Goliath saw in front of him was a pretty little boy; he didn’t recognize the anointing (God’s empowering) on David’s life. God’s anointing is on you to defeat whatever giant you are facing. The giant will try and get you to focus on what you don’t have (a sword or a spear), but remember that because God is with you, the odds are in your favour!
 
Your victory isn’t accomplished with carnal weapons. As David said, “the Lord does not save with sword and spear.” Carnal weapons can help – David didn’t just kneel and pray, he had a slingshot and he used it – but our faith and confidence should not be in them. God created whatever the doctors used to put the medicine together, and it can help you, but your faith needs to be in God. Medical science is limited; God isn’t. Whatever giant you’re facing, the world may have an answer for it – but remember that God’s ways are better than ours and His wisdom is far wiser (Isaiah 55:8-9; 1 Corinthians 1:25). To everyone else on the battlefield, David must have looked like a foolish, over-confident little boy. But his confidence was rooted in the faithfulness of God and the covenant he had with Him. This is the foundation which caused David to speak out his faith boldly!

“…for the battle is the Lord’s, and He will give you into our hands.”
1 Samuel 17:47 (NKJV)
 
God has set you up to reign in life and overcome the giants that you face (Mark 11:22-24; Romans 5:17; 2 Corinthians 2:14; 1 John 5:4) but you can’t just sit back and ignore the giant hoping God will deal with it. If you do that, the giant might kill you. Like David, you need to use the anointing on you (Acts 10:38; Romans 8:11; 1 John 2:27) and go kill your giant. God is with you and His anointing is on you to do it. David didn’t wait for God to strike down Goliath – David himself threw the stone but trusted God for the victory. David ran up to Goliath and took Goliath’s sword and cut off his head. He didn’t wait for God to do it, but he completely trusted in and relied on God for the victory. David knew that without the covenant (relationship) with God he could do nothing. Likewise, without our relationship with Jesus, we will never have true victory (John 15:4).
 
Passivity will destroy you. Don’t believe the lie that God will do it all. His anointing and empowering in you will do it through you. It’s 100% His ability. You just need to have confidence in His ability in you. You have God’s authority to deal with the giants (Luke 10:19; Mark 11:22-24) and so boldly speak out God’s Word and tell your giant (or mountain) where to go.

You can rest, knowing that God has given you the victory and He will lead you in triumph. He has set you up to reign in life and overcome every giant that you will face by giving you the anointing and authority to deal with them.