I should point out that while we are to cooperate with God, it is only by his grace that we are able to do so. We could not "earn" God's grace on our own, but neither are we irresistably overcome by it.
So we are capable of cooperating, by his grace, with God or rejecting him and his grace.
You cannot completely reject God's grace, thus to some degree it is irresistible. Even Satan is and acts in virtue of God's grace not merely in lack of it.
Many of the problems with theology come down to oddly extreme notions of God and language in general.