The Rapture comes as a Thief

Paul shows according to the wisdom given unto him that the day of the Lord coming as a thief is without “the times and the seasons” even knowable, which is generally how thieves show up in the night; without signs or indications. (1 Thes.5:1-3) The times and seasons of the final week of Daniel 9 and the restoration of Israel was not for us to know. (Acts 1:6-7)
When we compare Mark and Matthew’s accounts (Mk.13, Mt.24) about watching for the Son of Man, Jesus gave warning to watch for his sudden coming, and that he himself in the days of his flesh did not know when he would return. It could be as in any watch of the night, but that no man could know. (Mk.13:32-7) Matthew recalls that the sudden appearing will be like a thief, without any warnings or indications, as a snare. (Mt.24:42-51) “Watch therefore: for ye know not what hour your Lord doth come.” “Watch ye therefore... Lest coming suddenly he find you sleeping.” He spake this to all. (Mk.13:37) Paul said that they would think they are in peace and safety before the sudden destruction comes. (1 Thes.5:1-3)
What we see from the context here in Luke 21:35 is that there is a day coming upon the entire earth which will be like a snare. A snare is set without any sign or indication of its presence; thus unawares as the text states. (Prv.1:17, 7:23, Ecc.7:12, Psa.142:3) This is the “hour of temptation, which shall come upon all the world, to try them that dwell upon the earth.” (Rev.3:10) The entire world will be overtaken by this sudden snare and sudden destruction, which is marked by the sudden appearing of the Son of Man and a conditional escaping all those things listed by those that are worthy to stand before him. (Mk.13:36-7) “Because thou hast kept the word of my patience, I also will keep thee from the hour of temptation... Behold, I come quickly”. (Rev.3:10-11)

The admonition to watch is to watch for Christ himself to appear. (Mt.24:42-3, 50, 25:13, Mk.13:33-7, Lk.12:37-48, 21:36, Phil.3:20, 1 Thes.5:6, Tit.2:13, 1 Pt.4:7, 2 Pt.3:12, 1 Jn.2:28, Rv.3:3, 16:15)
If I tell someone I am coming to their house next year as a thief, will they know when I am coming? If they watch for me and they catch me as I am coming because they are looking, did that mean I didn't come as a thief?