It appears that Paul doesn't believe that being born again is the key to
being qualified to be taken in the Rapture.  However, Jesus said in John
3, twice for emphasis, "No one can see the kingdom of God unless he is
born again."  He did not say that in addition to being born again that
you must be living a holy life, and be watching for his appearing, etc.
These are works and we are never saved by works, but by the blood of
Christ, which cleanses us from all sin, past and future.

There are, however, some professing Christians who may be expecting to
be taken the the Rapture, who are not ready because they have never been
born again, and have never received the indwelling of the Holy Spirit.
They will be startled to be left behind at the Rapture.

Those who are truly born again should have no desire to live unholy
lives because of the indwelling effect of the Holy Spirit, but it
doesn't mean that they are still not of a sinful nature.  If the key to
be taken in the Rapture were a sinless life, then none of us would be
taken.

We must be careful that we do not include works in determining who
qualifies for the Rapture, because we are not saved by works.  May God
bless you!

Wes K.