"Necessary conditions" is a philosophical phrase that deals with states of affairs. Take, If Y then X: That X is a necessary condition for Y means that Y cannot exist without X also existing, since Y is a sufficient condition for X.
1. If I'm regenerate, then I'm united to the risen Christ.
2. If I'm united to the risen Christ, then I'm regenerate.
1 means that it is impossible to have regeneration without union with Christ. It also means that the absence of union with Christ guarantees the absence of regeneration. This also means that the presence of regeneration guarantees the presence of union with Christ. The same sort of logic applies to 2.
Both 1 and 2 are true, yet neither proposition implies the logical order (or temporal order) of union with Christ and regeneration. Nonetheless, in both cases the consequent is a necessary condition for the antecedent; so in 1 what is indexed to the necessary condition, namely union with Christ, is that which is tied to a sufficient condition, regeneration. Most Reformed Christians do not have a conceptual problem thinking in terms of regeneration as being a "condition" for union with Christ (since they appreciate that regeneration is logically prior to union with Christ, or the means by which one becomes united to Christ). In 1, what type of "condition" is regeneration? Well, it's a sufficient condition in 1. Accordingly, if in 1 regeneration is a sufficient condition for union with Christ, then the "then" of the proposition, namely union with Christ, must be a necessary condition for regeneration - since the state of affairs of regeneration cannot exist without union with Christ. It is necessary, in other words, that union with Christ exist if regeneration exists. Causality and logical order is not even in view.
James teaches: If I'm justified, then I have good works, which is to say, good works are a necessary condition for one who is in a state of justification. Such a statement, although true, would be rather uninteresting to one who is inquiring as to whether another believes that good works are the cause or grounds of his justification. The same can be said of love.1 Corinthians 16:22