To feel sorrow, pain, or regret
over something you have done
or left undone;
to be sorry for these sins,
ask forgiveness of God,
and then turn away
from that behavior
and do right.
...I did not come to call the righteous, but sinners to repentance...

..unless you repent,
you will all likewise perish.

For all have sinned,
  and fall short of the glory of God.

Matthew 9:13,
Luke 13:3,
and Romans