Why is it that there still people and some are Christian are still in doubt that GOD really exist?

It is a choice. They choose to believe anything other than the truth.

I haven't met a Christian that doubts God's existence, since they follow the teachings of Christ, who is God.

Let me answer that for you...WE HAVE NO PROOF that he exists. If he did then maybe some of us or maybe all of us would change our minds and our religion but i don't think that is going to happen any time soon unless something amazing happens where "God" Comes down and makes all human kind whole again!

Because there is no evidence for the existence of a god- any god. It really is that simple.

This is your GOLDEN OPPORTUNITY to prove that god really exists and convert more followers! I eagerly await your proof so I can convert!

I think I have a long wait.

A Christian (follower of Christ) would have to believe in God (Jesus).

Because all off the evidence says "No", In fact the evidence is so clear that the question is why does anyone believe in whatever god they believe in.

Because some of us overcame the brainwashing.Rational and critical thinking really is important.Try it.

They haven't really met the living God.

Doubt is healthy, blind obedience is not.