I at one time believed in the Calvinistic doctrine of limited atonement. This doctrine states that Christ died solely for his elect. Christ offers the gospel to all yet did not actually die for all. I have struggled through this doctrine for many years now. Despite the fact that this doctrine is exegetically unfounded, it has many negative practical implications.
First of all, with this doctrine one can never be sure if Christ actually died for him. I, for example, have doubted my election at times. How do I know if I am elect? And if I am not elect then Christ did not die for me! Ultimately then, the doctrine pushes me into looking at the eternal decree of God for my assurance. How can I tell if I am among the elect? The answer usually given is that I know by my faith. However, there is true and false faith, and I must test myself to see whether or not my faith is real faith. According to a reformed exegesis of Hebrews chapter 6, a false faith can still cause one to repent, taste the heavenly gift and share in the Holy Spirit. Ultimately, I must look at the quality of my works and see if they are Spirit wrought. My assurance is in my inner transformation, not in the gospel. There is simply no way around it; I ultimately never know if Christ actually died for me except for the amount and quality of my good works. I know that when I look inward, as when reading Jonathan Edwards' Religious Affections, I see my sin and simply doubt my faith.
A Calvinist will object that they believe in a "free offer of the gospel" because they are not hyper Calvinists. Thus, I can trust in this universal offer. However, I must ask: Is this really a universal offer? How can God offer something he has not actually paid for? Can he really tell me I can accept the death of Christ while it in fact has never been paid for me?
The other hard issue to deal with is in Evangelism. As a Calvinist I could not freely offer the death of Christ to unbelievers. I would make my way around it by saying "believe on Christ's death because he has died for believers". While this is true I could never look at an unbeliever and say "trust in Christ's work accomplished on your behalf!" If I were to see my brother in despair I cannot look them in the eyes and say "do not despair! His righteousness is yours! He has fulfilled the law and its curse on your behalf!" However, as an adherent of the Book of Concord I can proclaim to all men "believe upon Christ who has paid the penalty for your sin!"