You can “mix” with anyone as a catholic, how else does one evangelise the unbeliever?
When a person becomes a mason, they must take an oath to not sleep with certain persons wives, which in and of itself is immoral. This eludes to the idea that it is somehow okay to have sexual relations with others wives, just not the higher ups in the masonic organization.
Therefore the masonic organization is immoral from it’s very foundation, within it’s own oath.
This is one reason why catholic’s cannot be masons.
If you read the oath that you’re referring to, the whole thing refers only to actions taken with regards to Master Masons. So when it says not to have carnal relations with their wives, it is simply following the pattern of the rest of the oath, not giving implicit permission to sleep around.
All that oath is really guilty of is putting the Master Masons on a tier above other people with respect to your loyalties. While this still may not be desirable from our point of view, it certainly cannot be held against them, since there is precedence for doing that sort of thing in the Bible.
Consider Deuteronomy 24:7, which says “If any man is caught kidnapping a fellow Israelite in order to enslave him and sell him, the kidnapper shall be put to death. Thus shall you purge the evil from your midst.” Now, by the logic you applied to the Masonic oath, we would have to conclude that this verse is implicitly give us permission to kidnap, enslave, and sell a non-Israelite.
Personally, I don’t view this verse as giving us that type of permission. It, like the Masonic oath, is just taking a certain group of people (the Israelites, in this case) and putting them on a higher tier with respect to your loyalties. So I don’t really see any justification for interpretting the oath the way you did, unless you’re also going to apply that type of interpretation to other texts, like Deuteronomy, for instance.