The Greek word for "fit" in Luke 9:62 means usable.
This is talking about ministry in the kingdom - not for eternal salvation which is only found in Christ's finished work on the cross and resurrection alone.
2090. [FONT="Galatia Sil" !important]εὔθετος[/FONT] [FONT="Gentium" !important]euthetos[/FONT] adj
Fit, suitable, usable.
Complete Biblical Library Greek-English Dictionary, The - The Complete Biblical Library Greek-English Dictionary – Delta-Epsilon.
The "context" of Luke 9 is definitely talking about "ministry" in the kingdom.
Luke 9:60-61 (NASB)
[SUP]60 [/SUP] But He said to him, "Allow the dead to bury their own dead; but as for you, go and proclaim everywhere the kingdom of God."
[SUP]61 [/SUP] Another also said, "I will follow You, Lord; but first permit me to say good-bye to those at home."