You two are making no distinction between weather modeling and climate modeling.

Weather modeling involves predicting the distributions of air temperature and pressure, water vapor content, on time scales where such dynamical fluidic interactions can be predicted accurately. A few days into the future.

Climate modeling looks more into averages and more dynamically stable quantities. If you take a black sphere and place it in the sun, it gets hot today, tomorrow or 100 years from now. If it's always in the sun then you can predict the temperature of the sphere, given how much you know about the physical properties. Learning about all of the processes that affect how the light radiated from the sun is converted into heat, how it is transported, and reradiated is part of what scientists who study climate actually do. Others model the consequences given whats currently known.

As with many arguments that have their roots in anti-scientific dogma, you two are trying to magnify the uncertainty inherent in a very complex issue. Not only that, but to then imply that resonable understanding is unatainable and as a result, no human contribution to global climate change can ever be proven.