Next time you read through the book of Acts, pay close attention to who's name people were baptized in. You will notice that, in the places where it is specific, it is always in the name of Jesus. Never does it say that anyone was baptized "in the name of the Father, and in the name of the Son, and in the name of the Holy Spirit". And in Romans 6:3, Paul states that we were baptized into Christ Jesus. So, let's examine the Scripture and see what's going on.
In Acts 2:38, the Apostle Peter commanded the crowed to be baptized in the name of Jesus. And he was with the Eleven, who were all with Jesus when Jesus commanded the disciples on making disciples of all nations in Matthew 28:19. Nobody corrected Peter. The disciples that were with him who also heard Jesus' command corrected him. And neither did Jesus, either by vision or by angel. Jesus said that those who keep his commands are those that love him (John 14:21). Oh, and did I mention that in spite of this, those who were baptized still received the Holy Spirit? Further more, in some cases, it was because Peter laid his hands on the new disciples that they received the Holy Spirit (Acts 8:14-17)! What's going on?
Let's consider the evidence so far: Peter gave a command that is apparently contrary to the one Jesus gave, in front of ten others who should have been able to correct him. And not only did God himself not correct the error, he even performed miracles and gave the Holy Spirit through Peter, who is apparently in rebellion to Jesus' command. Does God honor those who are rebelling against him? Or does he honor those who obey him? He honors those who obey him!
Let's take a look at some more evidence. Let's take 1 Corinthians 1:14-17, where Paul says that he wasn't sent to baptize, but to preach. Didn't Jesus tell command his disciples to baptize when they preach? If this command is supposed to apply to all disciples who go out and preach (as the Church implies or even states as much), then that means Paul is also in rebellion, right? Or perhaps there's something going on that we're not aware of. Because Jesus would not give a command that's supposed to apply to everyone, only to contradict that by not requiring some to follow said command.
Let's take a look at the context of Matthew 28:19.
18 And Jesus came and spoke to them, saying, "All authority has been given to Me in heaven and on earth. 19 Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, 20 teaching them to observe all things that I have commanded you; and lo, I am with you always, even to the end of the age." Amen. [Matthew 28:18-20; NKJV]
Jesus said that all authority has been given to him, specifically. When you do something in somebody's name, you are claiming you have authority from that somebody to do what you are doing. Since all authority has been given to the Son, it means that only the Son has authority to do anything at all (except for the Father, who gave such authority). In other words, it is the Son who has the authority to baptize, not the Holy Spirit. And it is the Son who can give authority to his disciples to baptize nations on his behalf. So baptizing the nations in the name of the Holy Spirit doesn't make any sense. And since the Father delegated all of his authority to the Son, doing things in the name of the Father also doesn't make any sense, even though the Father still has all of the authority he gave to the Son.
Taking all of the evidence so far, it looks like somebody added to Matthew 28:19. If the command includes baptism, then taking all of the evidence we have, the passage should say, "Go therefore and make disciples of all nations, baptizing them in my name". And if the command does not include baptism (which the evidence suggests that it doesn't), then the verse should say, "Go therefore and make disciples of all nations in my name". If this is what the command was originally, then it fits perfectly with what we know the disciples did when they preached the Gospel. There was no correction to the error because the command that they were carrying-out was the command that was given! That also explains why God still performed miracles and gave the Holy Spirit through Peter, because Peter was doing exactly what Jesus commanded!
We don't have any of the original Greek manuscripts (or even the Hebrew from which it was translated), so the only evidence that we have that our version of Matthew 28:19 was modified is what is recorded in the rest of the books, and in Matthew 28:18. If the command given does include baptism, then it means that Trinitarian baptism is actually heresy. If the command given does not include baptism (which is probably the case), then Trinitarian baptism isn't necessarily heresy, but it also doesn't make any sense considering what Jesus said right before giving the command.