The church Jesus Christ said He would build (Matthew 16:18) was the "assembly" (Greek: ekklesia) of the early apostles, including Paul, who described himself as "one begotten out of due season," Barnabas and others, besides the original eleven, together with Matthias, who replaced Judas Iscariot. They continued to observe the weekly Sabbath, for which there is absolute, incontrovertible proof in the New Testament Scriptures. They continued to observe the annual Sabbaths, such as Pentecost (the "birthday" of the New Testament Church—Acts 2), the Days of Unleavened Bread (I Corinthians 5) and the Passover (I Corinthians 11). Luke mentions the "fast" (Day of Atonement—Acts 27:9) in about A.D. 55-56, long after the Ascension of Christ. They observed the Passover exactly as did Christ on the 14th of Nisan, or Abib, the first month of the sacred calendar.