If having the Spirit occurred simultaneously with exertion of belief, then Paul would not have asked if they received it separately from belief after they believed. Some believe that one must have the Spirit of God if one believes. God's Spirit is the seal. And the Spirit is put in us so that it can stamp God's image upon our lives. We have the seal in order to have ourselves changed into the image.
Money can only purchase that which is in the kingdom of the ruler whose image is on the money.
You cannot take a German coin and buy a chocolate bar in Canada. You need a Canadian coin to buy anything in this country. The image and seal indicates where that money has value. On the other hand, all antichrist's world is available for purchase by those who have the beast's mark or seal. God's Kingdom offers liberty.