What happens at the moment a person believes the gospel?
At the moment of believing the gospel, the Holy Spirit comes in, seals the believer as God's brand, and becomes the power of God within. This follows hearing the word of truth, the gospel of salvation, and the Spirit opening understanding; the believer is then under grace, led by the indwelling Spirit.
Les explains the order: every child of God comes from being a sinner, a son of Adam, condemned already. As soon as a person realizes this, they hear the gospel, the Holy Spirit opens their understanding, and they believe. The moment they believe the gospel, the Holy Spirit comes in. He becomes God's brand upon them and the very power of God within them. That is why they are not under law but under grace. Les clarifies that grace is never licensed and does not mean becoming lawless; instead, believers are led and guided by the dwelling Holy Spirit, not by the stringent demands of thou shalt and thou shalt not.