Really? What is your interpretation of what a "seal" meant in Biblical times? Do you really think that it had nothing to do with permanence? What did Kings use to finalize a message or a decree? What does the Pope use today? In the following verse, it is the wife speaking to her husband about their marriage:
Song of Solomon 8:6 : Place me like a seal over your heart, like a seal on your arm; for love is as strong as death, its jealousy unyielding as the grave. It burns like blazing fire, like a mighty flame.
Does that sound like a temporary seal to you? :) A seal is SERIOUS business. (See also Gen. 38:18) For goodness sakes, what do the seals in Revelation mean to you if they are not permanent? Are they subject to change?
Of course seals are serious! Did the seal on the tomb keep Jesus in there? Did the seals in Revelation keep God from His will being fulfilled? Seals are marking of someone belonging to God (in this case). But as we have plodded through already, WE can turn from God due to our free will. We can refuse God, refuse our seal, that first installment of the Holy Spirit. It seems inconceivable that someone would return to the vomit of their past life, but the reality is it HAPPENS. Despite the seal. God allows this seal to be broken, as He highly desires love from us, love which can ONLY be given freely. For love is not love if it is not free.
Regards