We tend to think that ‘successful’ evangelism means a sinner makes a decision for Christ after we share the gospel. If the decision is based on sincere repentance from sin and belief in Christ, it was. However, no all decisions are based on repentance and faith, but on other things, some of which represent material gain and some of which are based on all sorts of supernatural shenanigens we can experience.
On the other hand, I suggest that the Soverein reign of God over the salvation of sinners absolutely guarantees a 100% success rate for all of our human efforts at evangelism. Jesus WILL save all whom he came to save. The angel who spoke to Joseph in Matthew 1:21 told him, concerning the child in Mary’s womb, “. . . He WILL save his people from their sin, not that Jesus would only make salvation ‘possible’ for everyone who ‘makes a decision for Christ’.
Food for thought early on a Tuesday evening.