Mon Dieu

[Crack1]

Je crois en Dieu.
I believe in God.

Je crois qu'il m'a dit.
I believe what he told me.

Je ne crois pas qu'il m'a dit.
I don't believe what he told me.

Are my French sentences are fine?

[Neil Coffey]

The first one is fine.

The second is OK as the beginning of a sentence, but it doesn't quite mean what your translation says. You need to finish it off with something, e.g.

je crois qu'il m'a dit la vérité
I think he told me the truth

To say "I believe what he told me", use:

je crois ce qu'il m'a dit

Similarly in the negative:

je ne crois pas ce qu'il m'a dit