I've just taken a look at Messi's international list and it's as impressive or not impressive as Ronaldo.
Brazil, Chile, Mexico, Switzerland, Uruguay, has score against some nice countries, 2 against Spain which were in friendlies AFAIK? Bosnia and Servia in WC which are mid level teams but were WC goals.
Meanwhile Ronaldo has 3 against Netherlands in Euros, 1 in a semi final. Only guy to score a world cup hattrick against Spain, Switzerland as well, Denmark Belgium Hungary...
I don't get what people expect these 2 to do in international football? You play so little of it you barely even get the chance to go against several world class teams. Argentina faced France once, Portugal faced France once as well. Messi got 2 assists in the game, Ronaldo never had the chance to prove himself because he got injured.
I'm not sure what people expect, really. Ronaldo has more than proved himself at international level, and has played under the same circumstances others players have in the last 30 years and yet none of them have gotten 100 goals even though they also play San Marino and Gibraltar.
Messi has been a level below Ronaldo IMO! at country level but I watch Argentina games and he's the heart and soul of that team and you can hardly ask more of him, he does it all for them.
I just can't scrutizine things like so many guys do here. I love Ronaldo and will always love him more than Messi, but in the end I'd rather just enjoy them both and their achievements instead of underplaying things others modern player under the same conditions have never achieved.