What does it mean to be "open to God"? I know someone (who I pray for regularly that he would come back to holiness) who claims to be "open to God", and yet he is one of the most arrogant people I know. If someone is "open to God" then that person will be humble and willing to learn from others. He will also be steadily moving to become more and more in accord with what the Church teaches.
For some people being "open to God" is no more than to follow their selfish desires and blame them on God (because that makes it harder to criticize when you do that). In truth, that is not being open to God, that is being open to self. Here is a test you can take: ask yourself how you respond to criticism. If you are told you are doing something wrong do you immediately seek ways to justify your actions and avoid any changes? Then you are open more to self than to God.
God is constantly speaking to each of us, we just are not constantly listening. If someone is truly "open to God" then he will be listening more and more to God and changing his life to keep it in accord with the commandments of God. He will not be responding to clear commands of God with "that doesn't apply to me". Let us seek to become "open to God" and not get wrapped up in our own delusional self-justification.