In ancient Israel, the reason behind  flood of Noah's day had been lost, the covenant between God and Abraham had come and gone, the age of Judges and Prophets had past, and the people found themselves living in spiritual silence for 400 years.  Then the voice of the Elijah was heard calling for repentance.  We have reached what is referred to in Scripture as a fullness of time moment that calls for the return of Jesus for His people - His righteous church - His bride without spot or blemish.  Soon, very soon the spiritual silence will be broken by a trumpet blast from heaven, and salvation will cause the righteous to rise as judgment falls.