I have only self-studied logic a little bit, but let me take a stab at this.

First, let's review some terminology. (Source: The Power of Logic ISBN-9780078038198)

A **deductive argument** is one in which the premises are intended to guarantee the conclusion.

An **inductive argument **is one in which the premises are intended to make the conclusion probable.

Deductive arguments can be **valid **or **invalid**. A valid argument is one in which it is necessary that, if the premises are true, then the conclusion is true. An invalid argument is one in which it is *not* necessary that, if the premises are true, then the conclusion is true. A valid argument can have true premises and a true conclusion, false premises and a false conclusion, false premises and a true conclusion, or an unknown truth value. The one thing that a valid argument cannot have is true premises and a false conclusion. An invalid argument can have any of the above, even true premises and a true conclusion.

A **sound **argument is a valid argument that has all true premises.

A good lawyer should be able to construct a valid argument. But the soundness of his argument is determined by the jury. His argument will only be sound if all of its premises are true.

A **strong argument** is an inductive argument for which it is probable (but not necessary) that if the premises are true, then the conclusion is true. A **cogent** argument is a strong argument in which all of the premises are true. Note that a cogent argument can have a false conclusion.

To commit a **fallacy **in logic, is to construct an invalid argument. Wikipedia has a good list of over 50 fallacies.

Let's rewrite the argument in question into a well-crafted form.

- If the earth and the laws of physics allow humans to exist, then God must exist.
- The earth and the laws of physics allow humans to exist.
- Therefore, God exists.

This argument appears to be a substitution instance of the valid form called *modus ponens. *Therefore, it is formally valid. If its premises are true, then its conclusion must be true. In your opinion, you may affirm that the argument--although valid--is unsound, arguing (most likely) that the first premise is false.