Question: Can you be a Christian and be unforgiving?
Consider that Jesus taught his disciples to pray, "Forgive us our debts, as we also have forgiven our debtors." He further explained this by saying, "For if you forgive men when they sin against you, your heavenly Father will also forgive you. But if you do not forgive men their sins, your Father will not forgive your sins." (Matthew 6:12, 14-15)
So, that is a hard no. Try as I might, I see no way around it. And if you would like to explain to Jesus how impractical he is being, or rationalize with him on this, you can join Peter in doing the same thing, and feel the weight of Jesus' response in Matthew 18:21-35.
Now, before you panic, let me ask you another question: Even if you could hold on to unforgiveness and God's forgiveness at the same time, why would you want to?
By its very nature, unforgiveness prevents you from following through on many of the specifics of the Christian life and enslaves you to walk in the flesh rather than by the Spirit. Think about it. When someone wrongs you, does it stir up enmity, strife, dissention, bursts of anger, and disputes? Or does it stir up love, joy, peace, patience, kindness, goodness, gentleness, and self-control? Galatians 5 calls the first list the "fruit of the Spirit," and the second, the "deeds of the flesh."
Two warnings on this: First, forgiveness is not the same as reconciliation, so do not confuse them (reconciliation takes two people, forgiveness does not). Second, you do not "earn" God's forgiveness by being forgiving of others. These are distortions that steal the "good" and the "life" found in this teaching. So today, let us explore this, along with the good and abundant life available to you in God's demand that you, as an apple that does not fall far from the tree, forgive everyone of everything.