There are people who will tell you that the Bible “contradicts” itself. Most of the time if you press them for an example, they will not be able to name one. In other cases, they may throw out Matthew 5:17-20 as an example.
Matthew 5:17 Do not think that I have come to abolish the Law or the Prophets. I have not come to abolish them, but to fulfill them. 18 For I tell you truly, until heaven and earth pass away, not a single jot, not a stroke of a pen, will disappear from the Law until everything is accomplished. 19 So then, whoever breaks one of the least of these commandments and teaches others to do likewise will be called least in the kingdom of heaven; but whoever practices and teaches them will be called great in the kingdom of heaven. 20 For I tell you that unless your righteousness exceeds that of the scribes and Pharisees, you will never enter the kingdom of heaven. NET
If this is the only thing we have, then Jesus is saying that we must obey the law for salvation. On the surface, this looks to be in conflict with what Paul is saying in Galatians. Let’s start with “fulfill”. When you are in school, there are requirements to be met before you can graduate. Once you completed those requirements, you have fulfilled everything that needs to be done for you to receive a diploma. Here Jesus is saying that the Law has a purpose and that purpose is in effect until it was fulfilled by Him. How did this happen? With Jesus’ last words on the cross: “It is finished”.
Jesus lived his life in perfect obedience to God as the new Adam being put to death by those who are not obedient. (We might question whether these people merit forgiveness, but Jesus asks God to forgive them because they don’t know what they are doing). Just prior to His death, Jesus cries out “My God, why have you forsaken me?” God has put all the sins of the world onto Christ and as a result, God has to separate Himself from Jesus. At the end, His last words are: “It is finished” meaning that Jesus has fulfilled everything He came to do.
Jesus is calling out the scribes and Pharisees because they are pursuing righteousness externally without any change in their hearts (in Acts 7, Stephan calls them “uncircumcised in heart”). In his visit with Nicodemus, Jesus tells him that he cannot see the kingdom of God unless he is born again of the Spirit which implies something more than merely following a prescribed set of rules and procedures. This complicated and elaborate system the Pharisees and scribes are following makes getting into the good place all about scoring enough behavior points to prove your worthiness to God. The problem is this type of righteousness becomes more focused on worldly appearances and reputation than on God and as a result, it falls short. The changes brought about by our faith move us away from this worldly righteousness into something bigger. As these changes come from the inside to the outside, it would seem hard for us to not be able to exceed what the scribes and Pharisees considered righteousness to be.
Psalms 119:97 How I love your law! It is my meditation all day. 98 Your commandments make me wiser than my enemies, for your commandments are always with me. 99 I have more understanding than all my teachers, for your testimonies are my meditation. 100 I understand more than the aged, because I have kept your precepts. 101 I have kept my feet from every evil way, that I might observe your word. 102 I have not turned aside from your ordinances, for you have taught me. 103 How sweet are your promises to my taste, more than honey to my mouth! 104 Through your precepts, I get understanding; therefore I hate every false way. WEB
Would Paul agree with this? Absolutely, as long as we understand that the purpose of the Law is to lead us to Truth. In Romans 7, Paul tells us that the Law is holy, just and good and he wants to live according to the law but he can’t. At the end of the chapter, he asks who will rescue him from this body of death? Paul is describing the human dilemma that we all face.
Galatians 3:19 Why, then, was the law given? It was given alongside the promise to show people their sins. But the law was designed to last only until the coming of the child who was promised. God gave his law through angels to Moses, who was the mediator between God and the people. NLT
Both Luther and Calvin support the idea of law as a mirror that shows us as we are. This reflection shows us as always falling short. Luther was especially captivated by this idea. As an Augustinian monk, he lived every day with the idea that God would punish him for committing sin but then he read Romans and realized that God loved him in spite of his behavior.
The Bible assumes that you have read the Bible and know that angels are the messengers of God. There are signs that accompany a theophany (an appearance by God) such as earthquakes, thunder and of course, angels. Exodus doesn’t include angels but the fact that Moses doesn’t mention it doesn’t preclude it.
When studying a particular text, we should do two things. First, ask what is the text telling us. Second, is to put all of the texts that speak similarly next to the verse you are studying and compare them. We see angels in Isaiah 6, Stephan’s sermon in Acts as well as in Hebrews and Deuteronomy. The child (seed in some translations) of Abraham is Jesus. The God who called Abraham also gives us the Law 430 years later as part of the same plan.
Galatians 3:20 But there cannot be a mediator where only one individual is concerned. 21 God, however, is only one. Is the Law then opposed to the promises of God? No, indeed; for if a Law had been given which could have conferred Life, righteousness would certainly have come by the Law. WEY
No contradiction or opposition to the promises. If the law worked for salvation, there would be a contradiction.