Can Christians lose their salvation? (verses included)

Can Hebrews 6:1-8 happen to a Christian? Do you think it is possible for this type of christian to lose his salvation, or according to 1 Corinthians 5:5, will his spirit only to be saved and not his body? First I would like to say that Hebrews 6 is just as true as John 3. Sometimes we may not understand how …