The lattice energy for sodium iodide is 700 kJ/mol, while that for calcium sulfide is 2775 kJ/mol. Which of these salts do you predict has the higher melting point?
Melting something requires that you break its lattice structure and let it move somewhat freely as a liquid. Thus, the harder it is to break the lattice structure, the harder it is to melt the substance and higher the melting point.
As a result, the one with a higher lattice energy has the higher melting point.