Exodus 15

1 Singing is appropriate for glorifying God and commemorating His deeds. With this song, the people openly acknowledge that God alone has accomplished this amazing rescue.
2 They attribute their strength and their ability to sing to God. They credit Him with their freedom from slavery. They openly accept Him as their God and recognize that He is the same God who first gave these great promises to their ancestors.
3 The Israelites were weak and defenseless against the Egyptians. Even Moses had failed to be an adequate warrior for them. God, however, took up their cause and was victorious over their enemies.
4 The literal translation of "Red Sea" is "sea of reeds." Some critics use this to theorize that the Israelites merely crossed the sea at a shallow area and that the parting of the sea was a myth (see comments on Exo 14:22 and Exo 15:8). However, if this were true, then it would be exceedingly difficult to drown an entire Egyptian army in the same area. The next verse would especially have no meaning. A perfectly acceptable reason for this name would be that reeds grew all along the shore.
6 Since most people are right handed, the right side of anything is often considered the more powerful side. This verse does not necessarily imply that God has literal hands (He is spirit), but it uses a metaphor that expresses the strong action that God took against the Egyptians.
7 When the Egyptians enslaved the Israelites, they were looking after their own interests. When they refused to listen to God's command to release them, they were in open defiance against Him. God does not always take judgmental action against people in this lifetime for such defiance, but we can be assured that all accounts will be settled on Judgement Day.
8 The Israelites knew that the parting of the Red Sea was very unusual. The water appeared to have taken on some of the properties of a solid. Then, just as quickly, the water returned to "normal."
9 In their arrogance, the Egyptians thought they could conquer the Israelites despite God's obvious intervention and protection.
11 The "gods" referred to here may reveal that the Israelites were still pantheistic. While God tried to convey this message, the Israelites still appeared to have problems with the concept of monotheism. If we see this as a pantheistic confession, then they at least acknowledge that God is the greatest. Later phrasings of this sort take on the meaning, "how can other so-called gods compare, since they are just stone, wood, or metal?"

Freeing the Israelites certainly demonstrated God's ability to overpower men, but another purpose was to "judge" the false gods of this world. Each of the plagues in Egypt were designed in one was or another to defy the attributes given to the various gods of Egypt. Since the gods are not real, God does not judge them personally, but He does judge the faith placed in people, objects, and philosophies that are of no value in eternal and spiritual matters.

13 God is merciful to those who will follow Him (even if they have to be prodded along), but His judgement is harsh against those who refuse Him.
14 It is true that the surrounding nations would be afraid when they heard what happened. This is shown specifically in Joshua's attack on Jericho.
17 It is always good to remind ourselves what God has promised us.
18 This phrase indicates that God's "reign" would not have an end -- it would be perpetual. The definition of reign appears to have the idea of "ascending to the throne."
20 Using instruments to aid in worship of God is acceptable. Many petty arguments break out when some insist that particular instruments or particular styles of music are not suitable for worshiping God. However, we must remember that timbrels, harps, lyres, etc. were all used to worship God, yet they were also used to worship false gods and also found a home in "secular" music. The important thing is that the lyrics should always glorify God and/or be of spiritual value to people. There may also be times when certain styles of music are inappropriate or distracting, but those styles of music may have a legitimate use in other situations. We do not have to like all styles of music, but we should not condemn any type of music that is intended to glorify God simply because we don't find the style appealing. Worship leaders and musicians also have a responsibility to make sure that their music is appropriate to a gathering and to the occasion.
24 It is sad when people have witnessed God do something miraculous and then not respond appropriately. Just three days earlier they had seen God save them and they had composed a wonderful song of worship and praise to Him. Now they found themselves in a difficult situation, but instead of calling to God to save them, they complain, not just to, but against Moses. The people had been amazed and rejoiced, but their hearts were not changed. Sadly, there are many people who will go to church and sing joyfully, but their hearts are not changed and they do not truly trust God whom they have worshiped. Hardships can bring doubts, and doubts against God are sinful. Instead, hardships should bring about prayer based on faith. If things are not going well, pray first -- not complain!
25 Moses knows God and believes that He has the power to help. God does indeed have an answer.

Some have tried to figure out what kind of tree this was that could make bitter water palatable. I suspect that there was nothing in the wood itself that would have absorbed the bitterness. In the same way God used an ordinary staff to part the Red Sea, God used a piece of wood to clean the water. There is no special property in either of these objects, but it is God using these things as a conduit for His power that does the work. God, of course, does not need to use such objects, but He understands that the Israelites still can not "see" spiritual things. God gives the people something concrete to look at in the hopes that they will see past the people and objects involved and "see" God at work. In many respects the Israelites of Jesus' time were just as "blind" as these Israelites were. Also, most people today are likewise blind. In fact, the condition is so severe that even when God does do a great miracle, people will still not acknowledge Him, even if the miracle is undeniable.

The verse indicates that this water problem was a test for the Israelites. God can and will test His people to determine if they will really trust Him. The tests are not for His benefit, since He already knows what will happen, but the test is for our benefit so that we can see how much we have progressed in our relationship with God. Also, such tests may benefit (or hinder) those around us as they see us handle difficult situations with faith (or disobedience).

26 The Egyptians would not obey God and were subsequently punished. If the Israelites would obey, they would not be punished in this way. We know now that it is impossible for anyone to be in perfect obedience to God, and we are deserving of all of God's plagues. God's answer to our weakness was the death of Jesus on the cross.