can a christian who is saved decide not to be saved?

some christians might say that's not possible... if they are saved, they can't be unsaved. but what about free will? i think as long as you are trying to be good and have complete faith that Jesus will save you, then you will be saved. but i think if we respect free will and all the bible passages about falling away, it's possible to become unsaved. afterall, jesus said some seeds will start growing, only to wither and die due to worldly concern. and, Hebrews 10:26. ESV says 'For if we go on sinning deliberately after receiving the knowledge of the truth, there no longer remains a sacrifice for sins', to say they can't lose their salvation is like saying they can't choose to sin.