Acts 17:22-24 Then Paul stood in the midst of the Areopagus and said, “Men of Athens, I perceive that in all things you are very religious; for as I was passing through and considering the objects of your worship, I even found an altar with this inscription:
TO THE UNKNOWN GOD.
Therefore, the One whom you worship without knowing, Him I proclaim to you: “God, who made the world and everything in it, since He is Lord of heaven and earth, does not dwell in temples made with hands.
Paul's argument flows as follows:
You are very religious
Because you worship even the god you do not know
I proclaim to you the God you do not know
This God created heaven and earth
Several reasons argue against taking v22 as a sarcastic statement:
1: If the statement were sarcastic, the argument would not flow naturally to Paul's second point
2: The listeners, perceiving themselves as religious because of their many gods, would not have understood Paul's sarcasm if he was being sarcastic, and the use of sarcasm would therefore be ill conceived
3: Generally speaking, sarcasm is obvious in its context, and one needs strong reasons to assume someone is being sarcastic - such reasons are not found here
4: The statement about them being religious is true: they were devoted worshippers of several gods - they were simply serving the wrong gods. Sarcasm is the use of language which normally conveys the opposite meaning in order to convey contempt - the language Paul uses cannot be construed, by the definition of "religion", to convey any other meaning than the literal.
Whether Paul utilizes humor or irony later in the speech is another question. But there is no reason to read sarcasm into v22.