Nevertheless, simple acts have always separated people in fundamental ways. In the story of the Passover, the simple act of putting lamb's blood on the door posts of the house separated those who's firstborn lived from those whose firstborn died (Exodus 12-13). The New Testament equates this simple act with Jesus' saving us. He is the Passover lamb (1 Cor. 5:7) and his blood separates those who live in him from those who don't. The blood can only be on us if Jesus puts it there, and he chooses to put it on folks who are "washed."

Heb 10:19-22 Therefore, brothers, since we have confidence to enter the Most Holy Place by the blood of Jesus, by a new and living way opened for us through the curtain, that is, his body, and since we have a great priest over the house of God, let us draw near to God with a sincere heart in full assurance of faith, having our hearts sprinkled to cleanse us from a guilty conscience and having our bodies washed with pure water. NIV
Simmple things are often the point of separation, because they define who we are, what matters to us, where our loyalties lie, what our priorities are. I would have to say that "two men who feel the same way in their hearts and minds" will not be separated by baptism. If they truly feel the same way then either both will be baptized, or else neither will. If they truly feel (by this I think you mean believe) the same way, have the same respect for God's word and will, the same love of the Lord, then both will obey or not obey. But every individual does as they determine in their own hearts, and we can only evaluate what is done, not what's inside. As Jesus said, a tree is known by its fruit (Matt. 7:16-20). If someone says, "this is a fig tree" but you see apples on it, you know what they said wasn't accurate. I am persuaded that everyone who wants to please the Lord will be baptized, because Jesus said so, and his apostles said so over and over. The New Testament knows no Christians apart from baptism

And about people having the Holy Spirit come upon them before baptism, the only example is that of Cornelius household (Peter's preaching) previoulsy mentioned (Acts 10). A special demonstration in which the recipients were promptly commanded to be baptized. The one group event involving Paul and the Holy Spirit where baptism was a question is Acts 19:1-7 in which Paul encountered 12 disciples in Ephesus (probably taught by Apollos, Acts 18:24-28). He asked them if they had received the Holy Spirit since they believed, and they expressed complete ignorance. He then questioned their baptism and found that they had received "John's baptism" which was a baptism for Jews, involving repentance and forgiveness of sins (but no promise of the Holy Spirit or new birth or a new covenant relationship with God). Paul promptly instructed them about baptism into Christ, and they were baptized, and then Paul laid hands on them bestowing a miraculous manifestation of the Holy Spirit. Not only did those men need to be baptized to receive the Holy Spirit, they needed appropriate baptism, into Christ. Not merely a ritual, but a response to the authority of Jesus.

In the case of those twelve men (and all who will obey Jesus) this "simple" thing not only separated them from others who weren't baptized, it separated them from what they themselves had believed and been only a short while before. Since baptism takes folks from death to life, it truly is a separation, simple or not.