At first glance, Matthew 27:5 and Acts 1:18 seem to contradict. After betraying Christ, did Judas Iscariot hang himself, or just swell up and burst open?
Paul gives two signs of the Tribulation: The falling away and the appearance of the man of sin who sits in the temple in Jerusalem (II Thessalonians 2:3-4).
God, as our true Shepherd, provides total protection of His called out-ones forever. Being kept in God's name refers to assimilating the attributes of God.
The scope of the prophesied falling away is obviously international, affecting the entire world, involving a dramatic global rejection of even basic truth.