Does our spirit return to God when we die?

The soul is so constituted that it is able to take cognisance of whatever it is attracted to under all circumstances. But of necessity, there are a great variety of degrees. Every material form has its inner life, its spiritual life, its divine representation, and that inner, that spiritual, that divine, corresponds to the external. Therefore, all that finds expression on the earth in natural form finds expression also in the spirit land, in spiritual form, which corresponds to the external, the natural.

I do not believe you will ever reach that condition of perfection in the absolute that so many souls are so earnestly seeking for. There will always be a haven of rest in the future, a something better than that you have reached. 

There are an infinite number of very marked changes to be passed through in spirit, similar to the chemical change, which has been termed death. Spirits believe in the eternal progress of the soul, and believing this, they cannot see or realise any time or state of being where the soul can say to itself―I will go no farther, I am content, but on the contrary, the soul can only be happy by virtue of its own internal and external being―by constantly reaching out for something better than it has already found. 

You will find that as a spirit disembodied, you will constantly be called on to pass through changes distinct and marked, and changes that you will not realise in the external.

―Thomas Paine in Spirit