When writing about those "Left behind" very few understand or want to come right out and say it; that believers who are not "ready" when the Rapture occurs will be left behind to "have a share or portion" (in weeping and gnashing of teeth) with the wicked and hypocrites - in Great Tribulation. The difference being - their faith will be tested and made proof - even unto death whereas the ungodly are being judged and condemned.
 
The rapture is an event at the end of the Church Age to rescue the true Bride of Christ who is "worthy of Him."  Those who call upon the name of The Lord will be saved with the promise of Heaven when they die. But, not all who are saved choose to love Jesus first and deny themselves to follow Him. They are "unworthy" to be His disciples and therefore not becoming more intimately involved with Him.  Throughout history, without participating in the Rapture, true followers of Jesus have become His Bride because they are "counted as worthy" - to escape the things coming upon the earth, they are "worthy" to wear the Fine linen because of the righteous deeds of the saints and because they have "made themselves" ready when Jesus came for them. Only God knows who are the bride of Jesus and He will reward each of us according to our deeds done while on this earth. Those "Left Behind" are no longer "The Church" (this Age ends with the Rapture) so The Church - does not go through the Great Tribulation only believers who were not faithful, disobedient (acting wickedly) and sleeping when "their Lord" came for them.
 
We are not just to presume the high position of being seated next to Christ (there is a cup to drink or price to pay for this position) Which is given by God alone. Jesus asked His disciples if they were willing to drink of His cup - the five Foolish Virgins were not - taken in - but also not condemned either, they were told to go and buy (pay the price)  to enter.

A great picture of the Bride;  Eve was taken, removed out from Adam's body from a place  close to Adam's heart. Jesus, the second Adam, His bride will be taken, removed out from His Body. Not the whole body - but those whom God sees as being nearest to His heart.

Under the assumption that all who are in The Church are the Bride and will be raptured - the fact that God is Just and will render to each man according to what he deserves, that God disciplines and corrects all that are His children, that judgement first begins in God's house and numerous other warnings about who God is and what He requires - must be ignored.

None of us can assume the highest position in Christ but like the Apostle Paul we can all press forward towards God's highest calling for us in Christ Jesus who is the measure and stature unto which we are to attain - God will then decide who sits next to Jesus and then seat everyone else accordingly.  Ours is to Love, Honor, Obey and follow - to pray that we may be counted as "Worthy."