The treasurer invited Philip into his chariot. Note that Philip did not engage in a discussion with him. Instead he preached Jesus to the stranger. Preaching is not a discussion, instead it is an attempt to persuade a person to believe what is being spoken. The number listening does not turn a speech into a sermon. Rather it is the style and manner of the speaker which reveals whether it is a sermon or not. A sermon always calls for a response, for a decision in light of what has been said. The man from Ethiopia discovered he had asked an enthusiast into his chariot.
While we do not know the precise details that Philip said, it is obvious that he would have explained the verses that the treasurer was reading about the silent suffering of Jesus before his judges when he was denied justice, about where he came from (his generation) and why he gave up his life.
We can imagine the sense of wonder that would have filled the eunuch’s heart as he heard this explanation. He would have realised that Jesus had died in the place of sinners, that he had performed all that the powerless rituals of Judaism pointed towards, that he had been the sinbearer who had taken the place of sinners on the cross. During this sermon, the eunuch embraced the Saviour whom he had not known about a short time before.
Philip must have mentioned to the eunuch that Jesus expected all who believed in him should be baptised. This was the outward badge of Christian discipleship. As they travelled, they came to a spring or to an oasis, and with great enthusiasm the eunuch requested that he should be baptised by Philip. In passing, we should note that we should be enthusiastic about baptism. Not only is it the identifying badge of Christian disciples, it is also a means of grace through which Jesus brings spiritual blessings into the lives of his followers.
It is not necessary to assume that the man from Ethiopia was immersed. He may have been, but all we are told is that both Philip and the eunuch went down into the water. The ‘going down’ does not refer to the manner of baptism, but to their descent from the road into the stream or pool.
Immediately, the Spirit carried Philip away and the treasurer was left without his guide. The treasurer experienced the same situation that the church in Samaria did – his leader in the faith was taken from him. Luke’s readers must have noticed this feature and deduced from it that Jesus expects his followers to stand on their own feet in a spiritual sense very quickly.