Hi DixieNurse:
Good post.
You asked:
Can a person lose his or her Christianity?
Yes. I know because I lost mine.
You asked:
Is that the same thing as losing one's faith?
I don't believe so depending upon what one thinks faith is. I have come to understand that the faith that we receive from YHWH is the same faith that was in YaHshua. It's not ours to lose. Its the faith of YHWH in us that was given to us. It is ours if we accept it by putting it to the test to see if it is the truth of YHWH.
Otherwise, we reject the faith of YHWH that he gave us when we don't accept it and it is lost to us unless YHWH gives it to us again later.
Also consider that the faith we are given may not be the same faith that is given to another nor is it necessarily given to individuals in similar portions. Some people, such as Abraham, are given great faith and accept it. Others are given smaller portions. Lucifer was given a HUGE portion of the faith of YHWH and rejected it totally and is causing many of mankind to reject it in the same way through his current name of satan by deception.
So faith is not so much something we lose as much as something we can reject, if we don't accept it.
You asked:
What are we putting our faith in if we can believe in God one day, and not the next?
Our own faith is something that we got from another source other than YHWH, ie satan, etc. It tends to cause us to become confused of what faith is from the truth and what faith is from evil. We all run through this type of confusion at times depending upon whether or not we ask YHWH for wisdom so that we can choose wisely and seek out only His faith in us.
You asked:
If we do this, did we ever truly believe at all???
This I find very interesting because in understanding this as I do now it cleared up allot of confusion about faith and belief that I've had for, well, decades.
Simply put belief comes from our putting to work the faith we are given by YHWH. When we put that faith to work we learn more about it and YHWH gives us more faith as we understand one of His precepts and then another. He has us build His precepts one upon another in their proper order so that we can clearly see what His plan and the purpose of His plan is. It takes time and diligent searching to do this mostly because of the deceptions that satan has laid out for us and that we must overcome.
When we go through this process the knowledge of the faith we are given turns into understanding and then as we act according to that understanding our wisdom in YHWH grows. When that knowledge, understanding and wisdom reaches a certain level as determined by YHWH, then He knows, and we will know by the Spirit that He puts in us that we have proven His faith as being true. That is the point that establishes our belief in YHWH. Belief in YHWH is the proven-to-us faith of YHWH in us that we accomplish through our willing works of righteousness according to that faith.
Just as Abraham was justified by taking that faith of YHWH in him and wroughting it with works, he believed YHWH and YHWH considered him to be justified or righteous according to that beginning point of faith.
Faith and belief are just about the same thing except that belief is a special kind of faith; it is proven-to-us faith. If we don't do anything with the faith we are given then it becomes dead faith and is useless to us AND we can never believe YHWH as a result. ALSO, we can never believe YHWH if He doesn't give us His faith in the first place.
You wrote:
Personally, I don't believe God throws us away, so if one claims to be Christian one day, and something else the next, then I submit that it's not God's idea at all, but a man-made decision
The image of the Elohim ('God') in us, our mind, which is the combination of the 'spirit in man' and our brain interacting, is a so very precious thing of creation and YHWH is not about to waste even one of them. He will not give anyone any of His faith in this age unless He is satisfied that they will be permanently accepting it.
That is a piece of cake for Him to know of course as all of time stands before Him as if it is a single instant. YHWH indeed knows all of time. However it is very apparent that multitudes of people have been given His faith and have rejected it but that in itself does not lead to eternal death.
Eternal death would only result in someone acepting the faith of YHWH in him to the point of receiving the Holy Spirit of YHWH and THEN rejecting His Spirit by blasphemously throwing it back into YHWH's face. Again, I don't think YHWH would knowingly give someone in this age the Holy Spirit that will give it back to Him. Faith is rejectable to a point but the Holy Spirit isn't.
You wrote:
I believe too, that the grace of God is big enough to save a person with even the hardest heart, so it must be sufficient to keep a struggling Christian!
I was once a struggling Christian but overcame it to become instead a believer in YHWH and accepting the Blood of YaHshua so that the hope of righteousness in its fullness as it is in YHWH and YaHshua might become mine as well.
Grace is only possible through the righteousness of YHWH so YHWH will be doing only the right things to ensure that each and every one of us will be guided to decide to choose good and Life no matter what the amount of unbelief, and its resulting evil, has to be overcome.