The Scriptures above referred to, together with many others, show that Christ will reign during the Millennium, and we all know that Christ has not reigned yet. If Christ was reigning now we would not have the great systems of evil in the earth, for the Scriptures declare that when "His judgments are in the earth then the people shall learn righteousness." (Isaiah 26:9) The Scriptures in your question declare that "the dead in Christ shall rise first" at His coming. In harmony with this we see that then He will take unto Himself His great power and reign, as set forth in Revelation 11:17,18. Jesus Himself declared (Matthew 25:31), that His reign would follow His second coming.