In my experience with situations like this, the cause is usually a bad connection on the battery terminal. Often it will allow small draw like a door light, radio, etc, but not provide enough current for starting. Take your battery connections off. Clean them well with baking soda/water. Dry. Apply dilectric grease, firmly put the terminals back on, then tighten the connections well. This might help, and it certainly won't hurt.
Two doors, four doors, wagons, and ragtops.