Easter is only mentioned in the King James Version of the Bible (Acts 12:4 KJV). The modern versions like the NIV, ESV, NASB, and even the New Kings James Version all correctly use the word “Passover.”
Passover was an annual observance of the original Passover meal the Jews ate just before their departure from slavery in Egypt (Exodus 12). The original meal was a foreshadowing of the Lamb of God, Jesus, who would come as the ultimate sacrifice for the sins of mankind.
Easter, on the other hand, is a holiday that came down through recent history from western European paganism. It is associated with the spring equinox, when the daylight hours increase and new life in nature springs forth. Our modern Easter includes motifs of eggs and rabbits as a part of the celebration because of the focus on fertility in the holiday’s pagan roots. As with many of the pagan holidays, Easter became Christianized over time and today it is commemorated as the time of Jesus’ death, burial, and in particular, his resurrection. Christians all over the world celebrate Easter Sunday as a special day.
Romans 14 lays out the proper Christian perspective in regard to food, drink, and “special days.” It says, starting in verse 5, that “One man considers one day more sacred than another; another man considers every day alike. Each one should be fully convinced in his own mind. 6 He who regards one day as special, does so to the Lord” (Rom. 14:5-6 NIV).
Under the Mosaic Law, there were many feasts and Sabbath days that the Jews were required to observe. After some of the Jews converted to Christianity, they continued to observe the Sabbaths in light of the teachings of the Apostle Paul: they were now free from observing those days through the accomplishments of Christ, because he fulfilled the righteous requirements of the Mosaic Law through his death and resurrection. Still, some of the Jewish converts continued to observe the Sabbath as a special day in light of their history and the sacrifice of Christ. Nowhere in the Bible does Paul teach the Gentile converts to observe the Sabbath, but he is instructing them not to judge a brother or sister in Christ because they are now regarding the Sabbath as a special day “to the Lord” (Rom 14:10). When we acknowledge Easter as special because of the resurrection of Christ, we are doing so “to honor the Lord,” and that is in accordance with Scripture. It is not a sin.
For more information about Easter, see the link below.