Lets get this straight! Scripture provides proof of being "spiritually dead" but scripture never speak of spiritual death"???? So "dead" does not mean "death"??? I think you mean to say the Bible clearly teaches a state of spiritual death but it never speaks of THE ENTRANCE POINT INTO SPIRITUAL DEATH simply because we entered this world already condemned, already spiritually dead. So you deny any cause for fallen man entering into this world in the state of spiritual death????? If not, then what is the cause, because whatever the cause is, that is also the entry point.
So, you deny any beginning point into spiritual death in scripture? So, you deny the entry point of "death" into the world by one man's sin (Rom. 5:12) to be the entry point of spiritual death and thus there is no cause, there is point where spiritual death begins.
Death in its fullest meaning has its beginning point in one man in his one act of sin and "death" in its full meaning is what has been "passed" from Adam to all mankind and that is the origin of spiritual death cannot be found in us.