Is discussing and attempting to understand religious matters scientifically forbidden, and does it indicate a lack of faith?

A Muslim must believe in what is established in revelation, whether they understand its wisdom or not. It is not permissible for them to doubt what is established, nor to delay believing in it and acting upon it. There is no harm in attempting to understand the wisdom scientifically or intellectually, and in asking people of knowledge about it. One must be careful of those who do not possess knowledge straining to deduce wisdom, lest one ends up speaking about Allah without knowledge.