I've heard an objection to Calvinism along the lines of the title of this post many times. The argument is that "irresistible grace" is at odds with the nature of God, since God wants us to love Him freely. Paul Manata has a succinct answer to that kind of argument.
I would like to build a little on my friend Paul's point. Often we are told that Calvinism's teaching on irresistible grace is some equivalent to divine rape. This analogy is necessarily wrong. First, rape involves violation of the will of the rape victim. However, God's efficacious grace does not violate man's will, it transforms it. God's transforming act of regeneration is not coercion of the will (like a rapist), nor is it a fooling of the will (like a hypnotist). God actually changes the desires of a person so that they not only no longer hate God, nor imagine they love God, but actually love God.
Second, in addition to the fact that God commands love (which is my friend Paul's point, and he makes it effectively), God also threatens punishment to those who do not love. Roger Olson technically may be able to maintain his position that "it must be factually possible for both [parties] to a possible loving relationship to be able to say 'no' to the other" (p. 167 per Paul's post) even in the face of a command. After all, people in fact do say "no," to God's commands that we love God and love our neighbor. However, if this escape is employed the analogy breaks down. After all, we would still consider someone a rape victim if they gave consent only after a gun was pointed at their head, even if they technically could have said "yes." But the coercive power of the message of Jesus is even stronger than that: "But I will forewarn you whom ye shall fear: Fear him, which after he hath killed hath power to cast into hell; yea, I say unto you, Fear him." (Luke 12:5)
So, on the one hand, irresistible grace is not coercion and on the other hand God does (undeniably) employ coercion. So, the objection posed by Olson cannot stand both because it misses the mark and because it strikes a point that Olson must accept as true. Olson (and other non-Calvinists) have to admit that God employs coercion by threatening punishments on those who do not do as they are told. Yet irresistible grace is a means that God uses that does not itself involve coercion, but transformation.