Can you lose your salvation?

So this is a hot topic amongst the saved and I have my stance on this issue. I believe that you cannot lose your salvation. To say so undermines the work that Jesus did on the cross. John 3:16 says that if you believe on him you have everlasting life, how can you lose something that is everlasting? John 8:36 says who the Son sets free is free indeed. He did not say who is set free can become bound again. Also a grave error is those that take the position that you can lose your salvation are those that believe you must work for your salvation, which is against grace, which is the only way to get saved.
I believe that the correct question that should be asked is, were you saved in the first place?
The problem is many mistaken church going and knowledge of Christ as being saved, but its more than that, its your firm belief and love for Christ. God sees the heart and is most concerned with the heart above all things. If you look at the 7 churches in revelations, the worst ones were the ones that pretended to be saved, that looked saved from the outside, but were dead and cold on the inside. Is this not the same thing that the pharisees were doing, concerned about outward appearances.
We cannot lose our salvation because if that were true it says that Jesus dying on the cross was not enough, which is a lie, it was enough and it covers all sin! However, we must be wary and ensure that we were saved indeed. Back to John 3:16, fundamental to a Christ believing person is actually believing on the Son and if you do not, then you are not truly saved! Do you believe that Jesus was the Son of God and that he died and rose again for you sins? Remember if you do not accept the Son, you cannot accept the father which sent the Son, so please make sure that you are truly saved and once you are, you cannot lose your salvation!