Good afternoon, all.
    The answer to that question has to do both with our all too human
frailty and weakness, And with who Jesus is. Jesus offers to us
wretched sinners, total forgiveness and total acceptance. All this
"partial rapture" talk questions who Jesus really is; questions if we
can trust Him at His Word. Partial rapture-ism smacks of the
"Holyness" doctrine which says if Jesus comes when you are having a
bad day of discouragement, anger, doubt, you can't be raptured.  ...
That in the Holyness doctrine, you cannot possibly be raptured on that
day if you aren't perfect before God, and you will have to wait for
the second rapture-- or for the second coming.
   Jesus makes it very clear that once you belong to Him, you are His.
                           Romans *:38/39 says:
38 For I am persuaded, that neither death, nor life, nor angels, nor
principalities, nor powers, nor things present, nor things to come,
39 Nor height, nor depth, nor any other creature, shall be able to
separate us from the love of God, which is in Christ Jesus our Lord.

John 10:27-30
27 My sheep hear my voice, and I know them, and they follow me:
28 And I give unto them eternal life; and they shall never perish,
neither shall any man pluck them out of my hand.
29 My Father, which gave them me, is greater than all; and no man is
able to pluck them out of my Father's hand.
30 I and my Father are one.
         So, yes, dear brethren, once we have chosen to follow Jesus,
have accepted his shed blood in full payment for our sins, both past
and future, we are eternally secure in the hands of Jesus.
Lewis B