I’m not sure what relevance the eunuch is to this discussion. He was not born again - so yes, he needed help in understanding scripture and hearing the Good News about Jesus death, resurrection and being Born Again. When he heard the Word and BELIEVED, Philip baptized him. Scripture does not say specifically, but my assumption would be that he was filled with the Holy Spirit from that moment on as most Believers were filled with the HS in Acts. Otherwise, he could not easily grow his faith on his own back in Ethiopia. I suspect that when he read scripture from then on, the HS opened his heart and he understood it much more easily.
Also, note how active the Holy Spirit was in connecting someone seeking Truth with a Spirit-filled Believer that could share the Good News and get the eunuch saved.
Religion certainly did not, and could not, get the eunuch saved.
And one last time:
But when he, the Spirit of truth, comes, he will guide you into all the truth. John 16:13
It would take a theologian to misunderstand the above passage.
the eunuch shows the Holy Spirit provides someone to explain the Scriptures.
that someone is the same now as it was in NT times, THE CHURCH.
no verse in Scripture tells anyone to read the Scriptures and believe what they want.
Jesus established HIS CHURCH to teach and baptize.
read John 17 and see why unity in the Body of CHRIST is so important.