The Unexpected Moment of Christs' Coming

I Thessalonians 5:1-3

1  But of the times and the seasons, brethren, ye have no need that I write unto you. 
2  For yourselves know perfectly that the day of the Lord so cometh as a thief in the night. 
3  For when they shall say, Peace and safety; then sudden destruction cometh upon them, as travail upon a woman with child; and they shall not escape.