The Bible is the source for all things Christian, and it does mention Easter. In Acts 12:1, King Herod began to persecute the Church, culminating in the brutal death of the apostle James by sword. This pleased the Jews so much that the apostle Peter was also taken prisoner by Herod. The plan was to later deliver him to the Jews. Verse 3 says, “Then were the Days of Unleavened Bread.” The New Testament Church was observing these feast-days described in Leviticus 23. Now read verse 4: “And when he [Herod] had apprehended him, he put him in prison, and delivered him to four quaternions of soldiers to keep him; intending after Easter (i.e, 'Days of Unleavened Bread') to bring him forth to the people.”
However, this passage is not talking about Easter. The word translated "Easter" is the Greek word pascha (derived from the Hebrew word pesach). There is no original Greek word for "Passover," and it has only one meaning. It always means Passover - it can never mean Easter! For this reason, we find a Hebrew word used in the Greek New Testament. Once again, this Hebrew word can only refer to Passover. And other translations, including the RSV, correctly render this word "Passover."
Instead of endorsing Easter, this verse really proves that the Church was still observing the supposedly Jewish Passover ten years after the death of Christ! There are absolutely no verses, anywhere in the Bible, that authorize or endorse the keeping of Easter celebration...