Q. What day was the Pentecost? Was it on Saturday or on Sunday? I believe it occurred on Sunday. It's Pentecostthe root word "penta" means five or fifty for example, the pentagon has five sides. Now after Passover, there are seven weeks, and after the last Passover Sabbath, which was the 49th day, comes the day Pentecost, or 50th day.
So Sunday must have been when the Pentecost took place. In fact, the disciples were beginning the work as it was a customary workday then. They were beginning the work of spreading the gospel, just like Jesus rose on Sunday to continue His work as a High Priest. Christ rested in the tomb on the Sabbath, then commenced His work on our behalf when He rose Sunday morning.
Unfortunately, some people use the Pentecost as a reason to go to church on Sunday and ignore the Sabbath as a holy day. But that is quite a stretch. There is nothing in the Bible that says to keep Pentecost, Sunday, or even the day of Jesus' resurrection holy.
By that logic, we could keep Thursday as the Sabbath because that's when the Lord instituted the New Covenant at the Lord's Supper. You could even argue that it should be Friday, because that's when Jesus was crucified. Of course, Muslims keep Friday as their Sabbath.
But nowhere in the Bible does God pick any other day to replace the seventh day of the week. So I think it's pretty reckless for Christians to start altering the law of God, the one He spoke with His voice and wrote with His finger.
A very gifted minister said some very poetic things about Sabbath. He was preaching a wonderful sermon on the Sabbath. And then he said, "Now of course, that would be Sunday." And then he began to speculate on why, but he never produced a Scripture. Show me a Scripture that says, "Keep the first day as the Sabbath," and I'll do just that. But until I find that, are we going to take men's speculation over the very clear Word of God. The Bible says that the Lord blessed and sanctified the seventh day. He wrote it in stone with His finger He spoke it with His voice, saying, "Remember," meaning that we're not to forget it. We can't get away from the Word of God.