and to answer your question yes you can walk away from your salvation, if you turn back to sin willingly, paul states in hebrews ch. 10 that if you willingly sin after recieving the knowledge of the truth there remaineth no more sacrifice for sins, he goes on to state in Heb 10:28
He that despised Moses' law died without mercy under two or three
witnesses:
Heb 10:29
Of how much sorer punishment, suppose ye, shall he be thought worthy,
who hath trodden under foot the Son of God, and hath counted the blood of
the covenant, wherewith he was sanctified, an unholy thing, and hath done
despite unto the Spirit of grace?
If you truley repent of your sins and turn away from them and live your life through the spirit of god, you can overcome all sin, yes we fail as men but if you live by faith in god when you do fail the spirit will quicken you to repent of what youve done. There are to many "christians" who teach that you can sin all you want because jesus died for our sins but thats wrong. In John 5:14 and 8: 11 jesus said to go and sin no more so through jesus we can live without sin. Its not easy but possible.
But i like to remember that no matter what you do god will always give you one more second chance.
If you backslide god will always be there for he will never leave us nor forsake us.
check out the song one more second chance by ths band
http://www.silencingthestones.com