The context of Deuteronomy 16:1-3 indicates the focus of these verses is on the Night to be Observed and the Days of Unleavened Bread rather than the Passover.
At the time of Christ, because of historical deviation, some kept Passover at home at the start of the 14th and others kept it at the Temple at the end of the 14th.
The proponents of a 15th Passover discount clear scriptural details and instead speculate. One cannot build doctrines on implication, distortion, and traditions.
Passover takes place at twilight as the 14th of Abib begins. Unleavened Bread begins 24 hours later on the 15th of Abib. The Passover is a preparation day.
What happened to Israel after God sent her into captivity? Did God turn from physical Israel and begin to work with spiritual Israel, the church?
Nine steps had to be included with the Passover observance, all within the house until morning. It takes place between sun's setting and complete darkness.
Major reinterpretations have significantly distorted the meaning of Passover and Unleavened Bread, blurring the distinction between the two events.
The Bible gives many clues as to the location of the 'lost' Ten Tribes of Israel. With God's Word, along with historical records, only one conclusion is possible.
The annual reaffirmation of the covenant through the Passover is at the core of an on-going relationship with the Father and Son, beginning the perfecting process.
The Scriptures are largely silent about the exploits of the apostles other than Paul. We have only general comments concerning their spheres of activities.
We assess costs and values all the time in our daily lives. We should employ the same process to God's love for us in giving His Son as the sacrifice for sin.