"Good thing there is a resurrection from the dead! whew!"
What if on Judgment Day, God says to you: "You committed suicide...get out!"?
First of all, your direct question is flawed. It is not "suicide" to be killed for following a command of Jesus to make disciples out of all nations.
Second of all, your underlying assumption that suicide is the unforgivable sin is also incorrect. Nowhere in scripture does it state this. Therefore your question is to be rejected.