As a Christian, I believe in free will. Most Christians do. It's a key fact that helps us answer atheist objections like the problem of evil, and it's a vital aspect of our theology, explaining why sin exists in a world created by a perfect and Holy God in whom no darkness exists, and with whom no evil can dwell.
But many Calvinists disagree. Not all Calvinists, but many will say that free will makes us somehow more powerful than God, detracting from His sovereignty. "Who can resist His will?", they ask, misapplying Romans 9:19. Why do I say misapplying? Because both the existence of wills that are not God's own, as well as God allowing such wills to prevail over His, are explicitly and implicitly shown in scripture.
The most obvious of these is the very existence of sin. Sin, by definition, is that which opposes God's will. God wills a thing so much, He actively commands us to carry it out, yet we do not do so. How is this possible? Because God allows it. It is possible for God to will one thing more than another, which is why Jesus, being Himself God, is able to say to the Father "Father, if it is Your will, take this cup away from Me; nevertheless not My will, but Yours, be done." (Luke 22:42). Is God double minded? No. Are the Romans somehow stronger than God, able to take Jesus to be crucified against His will? No. The only conclusion, then, is that while Jesus, understandably, did not want to feel the wrath of God upon the cross, He did want to obey the Father, and the Father did want the Son to give His life as a ransom for many.
Furthermore, we see exactly how many Christ died for in verses like 1 Timothy 2:2-4, where we read that God wants all men to be saved and come to the knowledge of the truth. By contrast, the death of the wicked brings Him no pleasure (Ezekiel 33:11, 2 Peter 3:9). Everyone who perishes, therefore, perishes outside of the will of God.
Using scripture, I just explained why I, personally, am not a Calvinist, and why I don't think you should be either. Yet, under the most extreme versions of Calvinism, what just happened isn't honest Bible study with a correct conclusion. Rather, it is the will of God that I drew non-Calvinist conclusions. Who can resist His will? No one. Not even the Pharisees and lawyers in Luke 7:30, whom we are explicitly told rejected the will of God by refusing to be baptised. Therefore, I cannot become a Calvinist not because I am precluded by scripture, but because God wants me to reject Calvinism. And if Calvinism is true, this is correct.
But what if it isn't? What if what I just did genuinely is honest Bible study, and my conclusions are correct? In this case, Calvinists are actually resisting God's will themselves, getting their doctrine from a man, rather than from scripture as scripture says we should (Psalm 119; 2 Timothy 3:16-17). It is the greatest irony, therefore, that as far as the Calvinism debate goes, the only ones capable of resisting God's will are the Calvinists themselves. If Calvinism is true, then Calvinists and non-Calvinists are obeying the will of God, because they have no way not to. But if Calvinism is false, and an honest Bible study leads one to that conclusion, then only Calvinists are resisting the will of God, because it is not the will of God that they remain Calvinists.
Now, obviously non-Calvinists can also disobey God in this regard. One can always draw the right conclusions for the wrong reasons. I've debated many an Arminian who are Arminians simply because they hate Calvinism, and are actually quite resistant to scripture. Nevertheless, Calvinists, if Calvinism is false, still resist the will of God by remaining Calvinists in error.
But ultimately, Calvinists show they know Calvinism is false, because they maintain that they are Calvinists precisely because of honest Bible study, and they try to prove Calvinism with scripture. For example, Jeremiah 17:9: "“The heart is deceitful above all things, And desperately wicked; Who can know it?" But a Calvinist must understand that this includes their hearts. "But my heart is regenerate", they may say. Indeed. As is mine, and the hearts of all Christians, unless of course they contend that only Calvinists are Christians.
There really is no way around this, therefore. Either scripture is true, all of it, including the parts that draw one away from Calvinism, or Calvinism is true, and Calvinists have this special, unique enlightenment from God Himself that God has simply denied to all other Christians, who sincerely draw the wrong conclusion, because God has willed that they draw the wrong conclusion. What a messy theology.
My Calvinist brethren, I contend that you are, indeed, brethren, for you confess the Lord Jesus, and believe in your heart that God raised Him from the dead. Nevertheless, I also see a grave error in your theology, and it is one that causes much confusion and division in the Church. I encourage you to study the scriptures more closely, and see that while Calvinism may seem initially strong, there is much against it also. Therefore, you ought to step away from Calvin's confused theology, and ground your faith in the word of God.