why is it that i am an atheist yet i still say ,without even thinking ,thins like thank god?

No, it's not God's people brainwashing you, it's the philosophy of the world that has done this, the god of the world, the prince and power of the air got a hold on you and fed you many lies that you accepted. That's why you're Atheist. Instinctively we all know that God exists and this is why you might say "Thank God" sometimes.

"Thank God" is a popular ideomatic expression and has little philosophic relevance. If you are truly an Athiest, you will soon develop new expressions more appropriate to your non-religious thinking.

It's just a common expression that you learned along with all the other common expressions in English.

It is just a saying. I do not know many atheists that actually refrain from using phrases like this. Such as "thank God", "bless you", "Jesus Christ" and so on.

It's just a cultural thing that has been so ingrained into your psyche that you don't even think about it. Like the manners your parents taught you.

Same reason you say Thursday and Friday, even though you don't believe in Thor or Freya.

culture

it is ingrained in your background and social understanding

I can tell you anything you like about santa claus, because he is part of my culture, even if I dont believe in him

ask me about 'Diwali' and I could only give you the most basic answer

I find it funny! I do that too. I think it's just force of habit. who really cares though... it's just a couple words.

Its just a saying, nothing more to it than that.

I say it to, and I'm a proud Pastafarian.

It is just like any other saying.

That's all it is.