*I am not prepared to say that the Divine Mercy is from Jesus Christ.*
Just because this devotion didn't touch you/speak to you I don't think you have to try to ruin it for other people. You are putting a lot of energy into something you don't believe in. It's ok that you don't believe in this devotion -- maybe you have another devotion. I for one, do believe in this devotion. I am a very firm believer in this devotion. In my mind, in my heart I *know* that this is from Jesus Christ.
I am ending my participation in this thread.
We Byzantines don't practice special devotions to this or that, but rather devote ourselves to the corporate prayer of the Church found in the Book of Hours (Horologion), our equivalent of the old Breviary.