Summary: As Americans we are proud of our banner, the Stars and Stripes, but as Christians we have a much greater banner that is revealed to us here in our text.
Purpose: To describe how Moses exalted the Lord before God's enemies.
Aim: I want the listener to determine to lift up the Lord in their everyday lives.
INTRODUCTION: "It was Sep 13, 1814. A young United States attorney secured permission to board a British warship in an attempt to arrange the release of an American prisoner detained on Board. He was forced to stay overnight on the ship and from that exciting vantage point he witnessed the British bombardment of the fort which guarded the entrance to Baltimore.
"In the dwindling light of day he could see the American flag flying over Fort McHenry and as the darkness settled over the harbor he watched intently to see if the proud banner was still there. The red glow of exploding ammunition kept bringing Old Glory in view. When the gray dawn finally broke, the morning sunlight seemed to wash away the smoke from Fort McHenry and the silver stars and red stripes wore a new look of hope and courage. It was a magnificent moment in history.
"The young lawyer, Francis Scott Key, was so moved that he pulled an old letter from his pocket and wrote on the back of it these stirring words: 'Oh, say, can you see, by the dawn's early light,/ What so proudly we hailed at the twilight's last gleaming,/ Whose broad stripes and bright stars, through the perilous fight,/ O'er the ramparts we watched, were so gallantly streaming!/ And the rockets' red glare, the bombs bursting in air/ Gave proof through the night that our flag was still there./ Oh, say, does that Star Spangled Banner yet wave/ O'er the land of the free, and home of the brave?'" 
As Americans we are proud of our banner, the Stars and Stripes, but as Christians we have a much greater banner that is revealed to us here in our text.
Like with Francis Scott Key, times of war seem to make banners very important. So it is here in Exodus 17. Here we have the very first battle that the Israelites had to fight since they left Egypt by crossing the Red Sea.
Why did they have to have a battle? Couldn't the Lord take care of their enemies like He did the Egyptian army?
The answer is in Romans 15:4 For whatever was written in earlier times was written for our instruction, so that through perseverance and the encouragement of the Scriptures we might have hope. (NAU)
The question for us is:
► I. Why Must Believers Battle?
Let's begin by catching up on who the Amalekites were and what happened between them and the Jews. "AMALEK [AM uh leck] (warlike) a grandson of Esau ... Amalek gave his name to the AMALEKITES."
Esau was the twin brother of Jacob who later was named Israel. Jacob, the younger twin, stole his older brother's birthright. Later in life those brothers reconciled, but the descendents of Esau never let it go. Many years have passed, but the bitterness is still there.
"The main territory of the Amalekites was in the Sinai peninsula and in the Negev, the southern part of present day Israel. But they roamed widely throughout the territory later settled by the people of Israel. Throughout the Old Testament the Amalekites were bitter foes of the Israelites.
"Eventually the Amalekites gained a mountain in the land of Ephraim. King Saul of Israel won this area back and then chased the Amalekites from the land <1 Sam. 14:48; 15:1 9>. But Saul did not destroy the rich booty of livestock as God commanded and was rebuked by the prophet Samuel <1 Sam. 15:10 33>. [Ironically, Saul was eventually slain by an Amalekite.]
"The Amalekites continued to raid Israel. David attacked and defeated them <1 Sam. 27:8 10>, but they countered by raiding Ziklag and carrying off two of David's wives. He pursued and defeated them <1 Sam. 30:1 31>, executing one of them for killing Saul in an earlier battle <2 Sam. 1:1 16>.
"In the days of Hezekiah, 500 men of the tribe of Simeon defeated the Amalekites. Consequently, the Simeonites took their land and the Amalekites became a dispossessed people <1 Chr. 4:39 43>." 
"It was a descendant of Agag,[a king of the Amalekites that Saul should have killed] Haman, who tried to exterminate the Jews later in Esther's day (cf. Esth. 3:1, 6)"  The book of Esther tells us the story of how the last of the Amalekites were finally destroyed.
Why did the Jews battle the Amalekites for hundreds of years?
► A. Because God is at war with Satan
Look at verses 14 & 16, the battle is ultimately between God and Satan. "The ongoing problem with Amalek was not merely one nation hostile toward another, it was a war between God and Amalek."