I find it interesting that both of you want to debate my interpretation but neither of you have posted your own interpretation
(ugh...I wrote this once already but I guess it got lost in forum purgatory)
In this passage of scripture you find a number of examples of people who declare their willingness to follow Jesus in a manner of discipleship. However, each gave an excuse as to why they can't come quite yet because they want to finish something first. As a result of wanting to remain in their own lives, rather than follow Jesus, He told them that if you look back to your old life, then you are not fit to follow Him.
In contrast, consider Matthew 4:18-22:
"Now as Jesus was walking by the Sea of Galilee, He saw two brothers, Simon who was called Peter, and Andrew his brother, casting a net into the sea; for they were fishermen. And He said to them, Follow Me, and I will make you fishers of men.
Immediately they left their nets and followed Him. Going on from there He saw two other brothers, James the
son of Zebedee, and John his brother, in the boat with Zebedee their father, mending their nets; and He called them.
Immediately they left the boat and their father, and followed Him."
To me, this verse describes a persons worthiness of service, not their state of salvation.