Words like "merciful" and "compassionate" are common, indeed central terms for the LORD in the Bible. Indeed, what is arguably the highpoint of the Old Testament revelation of God's character -- a passage echoed through the rest of Scripture -- the revelation of the glory of the LORD and his declaring his name to Moses, includes at its heart

"The LORD, the LORD,
the compassionate and gracious God,
slow to anger, abounding in love and faithfulness. . "

(Note that the same word translated "compassionate" above is in other versions rendered as "merciful".)

From the Christian perspective, God truly IS compassionate, gracious, merciful, in forgiving sins -- and this is at the heart of their believe that God shows his mercy and forgiveness through the cross of Jesus, his Son.

So Islam borrowed the terminology and a part of the view from the Jewish & Christian Scriptures.

Now I won't go into it in detail here, but Christians would argue that the Islamic view of God actually contradicts their use of this terminology, for he turns out to often be simply arbitrary. So why shouldn't Christians use these expressions to try to point out that what the (borrowed!) Islamic titles proclaim is actually found in the Christian faith, not in Islam.

There is no such thing as an atheist.

Holy crap, I don't exist?

Or maybe you're wrong.

But I'm an atheist

There is no such thing as an atheist.

My guess is what as attempt to be ecumenical. I was listening at work, and was curious to see if he ended his prayer in "Jesus name" but missed that portion due to a phone call.

No but he said the Lords Prayer, he's gonna get sued.

I think in general most pastors seek to tone down the specifics and be more inclusive in these situations, and I hardly see it as some secret announcement that they believe something else.