Consider the diverse majors offered in our colleges. Think of all the various professions. Imagine whatever skills, specialties, and talents a person may have or hope to master. Whatever you come up with, you will not escape the bottom line necessity to master three skills: "reading, 'riting, and 'rithmatic". If a person only learns to read pictures/signs, write by tracing/drawing valuable symbols, and count their own money, they will at least have done the minimum to prove my statement true.
In many ways, the same can be said of the gospel. There are certain things that we cannot avoid if we want to share the message of the cross. Likewise, if we are serious about evangelism, there are topics we will naturally become fluent in and discipline will make us comfortable talking about (even though most won't want to hear you). In the book of Acts, there are three such topics ("there's always three") that I will call the Three R's for the book of Acts due to how readily they reoccur.
Resurrection... It's inescapable. Anyone just casually reading through Acts can't help but recognize how often Peter, John, Paul, etc. refer back to the resurrection. On one level, Christ being raised serves as the seal of approval of the Father upon Him. A risen Jesus, as Peter would argue, is proof positive that Psalm 110:1 has been fulfilled and that Jesus is in fact, both Lord and Christ.
And at a more raw and gut level, the resurrection serves as a divine rebuke. Think of it- when the question is asked how a lame man stands healed, here is the answer given:
It is by the name of Jesus Christ of Nazareth, whom you crucified but whom God raised from the dead, that this man stands before you healed.
Acts 4:10 (emphasis added)
The earliest recording of apostolic preaching includes using the resurrection as a hammer. It jolts the listeners to recognize the terrible wrath of God against their sin: the crucifixion of Christ. It also informs them that their work of putting Him to death has been undone by the One Who raised Jesus: none other than God. This sets up the need for the next R.
Repentance... The flow from resurrection to repentance is most clearly seen in Peter's address from Acts 2. Upon pronouncing Jesus as "both Lord and Christ" by evidence of the resurrection we read this response from those in attendance:
"When the people heard this, they were cut to the heart and said to Peter and the other apostles, "Brothers, what shall we do?" Peter replied, "Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins..."
The call to repentance is all through the book. And while Peter is busy prosecuting the Jews for their sins, Paul isn't letting Gentiles off the hook. In the context of their idolatry, Paul explains to the crowd in Athens,
"In the past God overlooked such ignorance, but now he commands all people everywhere to repent."
But today, repentance is a dirty word in many pulpits. "Why beat people up and remind them of their sins? They already know their not perfect" many say. And while that may make sense to some, we have to continually demand an honest answer from ourselves to this question: am I making this up as I go along or am I taking my marching orders from the Word of God?
Think about it- once commissioned to spread the gospel to all the world, the tiny band of the faithful Jesus left behind adopted the most ridiculous strategy ever: tell people how bad they are... they're sure to come running. It's not exactly a strategy for church growth (numerically) but it is the truth because there's no need to repent unless you're a sinner. It's totally counter-intuitive, but then again, do we still believe that God's ways are not our ways or are we forcing our way and calling it "Spirit-led"?
Relentless Resilience... In chapter 4 they were warned. The fifth chapter records the flogging of the apostles. Stephen became the first martyr in chapter 7. In chapter 8, the church leadership stays in Jerusalem while vast numbers of believers are forced from their homes due to persecution. Peter is called on the carpet and has to manage a near schism of believers in chapter 11 and is soon imprisoned in chapter 12. Paul is dragged out of the city of Iconium and left for dead in chapter 14. The very next day, he and Barnabus leave for the city of Derbe and preach there. I've barely covered half of the book!
How did they overcome all these odds? Why did they persevere and persist in their faithfulness to Christ and to the gospel of God? The Holy Spirit had convinced them of the truth and meaning of the Resurrection and had been transforming them through a lifestyle of repentance. The external reality of Jesus' life and the internal change that is brought through repentance gave them the incentive and immutable impulse to keep going despite the trials before them.
Is your life in Christ lacking the fervor and passion resembling the relentless resilience of the early believers in Acts? If so, you'll do yourself a service by revisiting the doctrine of the resurrection and seeking the grace of God to repent from sin and turn toward Him.