The answer to this might seem very easy to some people. The Arminian might respond, “Repeat the words of this simple prayer after me”, or “Just ask Jesus into your heart”.
Others might say, “If someone is not a Christian, then they are dead in trespasses and sins and so can’t do anything”.
I believe what Jesus said in John 6:44 “No one can come to me unless the Father who sent me draws him.” But on the other hand Jesus very frequently told people to come to him, implying that this choice was available to them.
We have to maintain the tension between:
- on the one hand that God is sovereign, salvation is his work, and he saves whom he will,
- and on the other hand that we are both responsible and active in the process. (We do not wake up in the morning to discover God has made us a Christian overnight.)
The starting point must be that the Holy Spirit is working in a person, even before they are born again (otherwise they would have no spiritual interest). It is possible to resist the Spirit (Acts 7:51) up to a point, but ultimately God can break through any resistance (e.g. Paul’s salvation).
The second assumption is that the words of the gospel are like seeds which the Spirit can bring to life. So we don’t tell people that they are required to trust in Jesus yet cannot. We tell them to trust him with the confidence that the Spirit is the one who gives power to these words.
The third assumption is that assurance is the work of the Spirit, not our job. So we don’t say, “Now you have prayed this prayer, you are a Christian.” We say, “keep seeking God until you know you have a new spiritual life within you.”
So now back to the question itself—what must a person do? The simple answer is “repent and believe”, but this needs some explanation, and raises an important question, “How much do you need to know to become a Christian—is there a minimum?”
I think there are three things you need to know:
- Who God is
- What God offers
- What God requires
Here are my thoughts, taken from an outline of a sermon on: "What does a person do to become a Christian?"