"Once saved, Always Saved!"
I read an article that argued that we could sin away our salvation. 
Do we all sin? Yes, I do, we all do, but Jesus' blood was the absolute payment for our sins, past, present, future. 
John 10:29 says it all. 
If we have been truly saved, we will sin, but no one can take us from the Father’s Hand, read Philippians 1:6, amen?