Of course credit cards are viewed as credit. If you're using money on a credit card, you are not directly paying for your transactions on goods/services immediately: this is the act of **borrowing** credit to pay for them.

Debit cards, on the other hand, work where the funds are taken from an account immediately (or subject to a small delay - but usually no more than 24 hours - depending on various factors).

You should never miss credit card payments, as that will affect your credit rating. If you have unpaid money on your card this is **debt** - plain and simple.

But to answer your question succinctly - yes, credit cards are a form of credit, as the name suggests. When you apply for a mortgage any unpaid credit (debt) is considered and would adversely affect you if you have such debts. The level to which it affects you depends on the amount of debt.

*This is how it works in the UK, but to my knowledge it is the same in the US and most other countries. Please clarify if you think this is incorrect.*