*Edit*

@Alex, he’s using the right word because he’s in the process of forgiving his enemies and it’s written in present tense (happening right now) and doesn’t need a helping verb. However, the word “forgiven” which is a past participle verb is used if he has fully forgiven all his enemies, plus, grammatically, it needs a helping verb (has or have) to complete the title. For example, the title would read: Has Forgiven All My Enemies (H.F.A.M.E.).