Catalyzes the reversible oxidation of CO(2) and methanofuran (MFR) to N-formylmethanofuran (CHO-MFR). Can only oxidize formylmethanofuran. This enzyme is oxygen-labile. H2O + N-formylmethanofuran + 2 oxidized [2Fe-2S]-[ferredoxin] = CO2 + H(+) + methanofuran + 2 reduced [2Fe-2S]-[ferredoxin] One-carbon metabolism; methanogenesis from CO(2); 5,10-methenyl-5,6,7,8-tetrahydromethanopterin from CO(2): step 1/3. This enzyme is composed of seven subunits FwdA (65 kDa), FwdB (53 kDa), FwdC (31 kDa), FwdD (15 kDa), FwdE, FwdF and FwdG. By growth on tungsten or molybdenum under anaerobic conditions. Belongs to the FwdC/FmdC family.