I used PayPal to buy Minecraft, and PayPal is very secure. If MOJANG sells your credit card number to korean gangsters its your own fault for using your credit card on the internet. PayPal and debit cards are safter alternatives to credit cards, so there is no excuse for getting your card num stolen.
OT: It's secure. Even with credit cards. Trust me, I bought it with a credit card and NOTHING has happened, though I myself often gamble with Korean gangsters so I'm bankrupt anyways (lolo kidding bro)