Beat your plowshares into swords, and your pruning hooks into spears: let the weak say, I am strong. Joel 3:10 (KJV)
We really are not sure what the weakness that Paul spoke about, but he considered his weaknesses to be a thorn in his flesh. To Paul, the thorn was a tormenting messenger of Satan. Although Paul pleaded for its removal God responded with
But he said to me, "My grace is sufficient for you, for my power is made perfect in weakness." Therefore I will boast all the more gladly about my weaknesses, so that Christ's power may rest on me. 2 Corinthians 12:9
Paul could have made himself out to be a spiritual giant in his day, being caught up into heaven where he saw and he heard things that he was forbidden to talk about. Perhaps the thorn in his flesh was to remind him that he was a mere man, and no better than other men.
He was constantly reminded of his human condition and found he was a weak man in the sight of God. He was subject to making mistakes being insulted, suffering in hardships, knowing the reality of persecutions, and having difficulties occurring like we face in our lives. He was constantly on the front line in a battle to win people over to Jesus and God gave him revelation after revelation. He was a person Satan persecuted to stop his advances. Yet Paul stood firm saying I can do all things through Jesus who gives me strength (Philippians 4:13.)
When Paul wrote to the Ephesians he gave them a mental picture of the body armor of a roman soldier likening it to the spiritual armor of God. He said that our battle is not with the men of this world, but against the spiritual forces of evil in the heavenly realm. (Ephesians 6:10-18) To the Corinthians he said we do war as men do, the weapons we use are divinely derived and inspired. (2 Corinthians 10:3-5) We are involved in a spiritual war that Satan is waging against those who obey God's commandments and hold to the testimony of Jesus. (Revelation 12:17)
As men we only see the surface of things for we do not see what is going on in the spirit realm. No one has seen the spirits (demons) at work producing the fruit of evil but we have seen the evidence of evil displayed throughout this world. The weapons of this world were designed to destroy the things of this world but they have no effect in the spirit realm. We are fighting a spiritual war with the powers of darkness that we cannot see but we are using weapons of the spirit world by faith to overcome evil.
David was a man after Godís heart but he fought a number of battles to establish the nation of Israel. A number of those battles were recorded and one common ingredient was found in each one. He sought the Lord for guidance before going into battle. One of his more famous battles took place before he became king during the time Saul reigned. In a battle with the Philistine army a giant of a man came forth and defiled the name of Israelís God.
David heard the insults of Goliath, which stirred his zeal for the Lord rather than shrink in terror. He was offered Saulís armor, which proved too much and then his own brothers ridiculed him. In his zeal for the Lord he stopped long enough to choose five smooth stones from the stream and calmly approach the Philistine. One look at David and Goliath said to himself ďyou canít be serious. You are sending a teenager at me with just a sling?
David said to the Philistine, "You come against me with sword and spear and javelin, but I come against you in the name of the Lord Almighty, the God of the armies of Israel, whom you have defied. This day the Lord will hand you over to me, and I'll strike you down and cut off your head. Today I will give the carcasses of the Philistine army to the birds of the air and the beasts of the earth, and the whole world will know that there is a God in Israel. All those gathered here will know that it is not by sword or spear that the Lord saves; for the battle is the Lord's, and he will give all of you into our hands." 1 Samuel 17:45-47
David understood that he was a mere boy who was the servant of the Lord. He understood the possibility of losing his life at the hands of Goliath but he placed his trust and life into the hands of God. He went in the name of the Lord knowing that the power of God is able to overcome anything the enemy can throw at you.
It is not by strength that one prevails; those who oppose the Lord will be shattered. He will thunder against them from heaven; the Lord will judge the ends of the earth.1 Samuel 2:9-10
It was not by their sword that they won the land, nor did their arm bring them victory; it was your right hand, your arm, and the light of your face, for you loved them. Psalms 44:3
"This is the word of the Lord to Zerubbabel: 'Not by might nor by power, but by my Spirit,' says the Lord Almighty. Zechariah 4:6
Yet I will show love to the house of Judah; and I will save them - not by bow, sword or battle, or by horses and horsemen, but by the Lord their God." Hosea 1:7
All those gathered here will know that it is not by sword or spear that the Lord saves; for the battle is the Lord's, and he will give all of you into our hands." 1 Samuel 17:47
What makes a Christian strong is the unyielding confidence in the power of God to deliver them from influence of Satan and spiritual war. We fight the good fight of the faith by looking to God and his promises for deliverance.
They overcame him by the blood of the Lamb and by the word of their testimony; they did not love their lives so much as to shrink from death. Revelation 12:11
The weak are those who all their lives were held in slavery by their fear of death. If anything they have grown accustomed to the corrupt morals of the world and consider everything they do right in their own mind. They stand condemned already because they do not trust or believe in the name of God's one and only Son. (John 3:18)