You have to take everything into account.
Messi benefited from that ridiculous Xavi-Iniesta axis. Sure, Ronaldo didn't exactly play with poor players, but they were not on Xavi and Iniesta levels. Then, Messi had an outrageously talented twosome to play alongside in Neymar and Suarez as well! I'm sorry, but Bale and Benzema just do not compare. That into account, even Ronaldo getting anywhere close is astonishing, never mind surpassing him. This is also completely excluding his time at United - while Messi was playing with Ronaldinho, Eto'o and the like in 2005-6, Ronaldo was playing with the likes of Kleberson, Djemba-Djemba and Alan Smith...