This is not, of course, to suggest that Philip was not religious. Simply that the congruence of religion and the removal of a dangerous enemy (to whom he had suffered an uncharacteristic reverse in the field) was likely too good to pass up.
In a world minus television and newspapers, one had to advertise oneself wherever that might be feasible. The comfortable bed-clothes of panhellenism and patriotic revenge served nicely to warm over their colder occupant: Macedonian imperialism. But, how to advertise oneself?
As today - nothing changes - in ancient times the Olympic games were about politics, cheats, money and, just to keep the interest up, athletic competition. After his crushing victory over the Greeks at Chaeronea in 338, Philip thought it wise to buy some ancient air-time. He ercted the "Philippeion" at the sanctuary of Olympia. It remains in the sanctuary today...

As can be seen, it will have made a rather impressive sight when completed by Alexander. Even more so with the full size statues of the royal family within.
It was a lesson not lost on the Diodachoi and their successors. Over the years following Alexander's death, they too donated gymnasia and such - the ruined remains of which are still to be seen. And not only to Olympia. Delphi and Athens benefited and Thebes found itself rebuilt.
Possibly one of the best, though, was the marvellously restored Stoa of Attaus in Athens:

Can't think of better way to advertise that, far from being an "Oriental despot", Attalus was, in fact, a highly cultured individual with the good of Athens in his heart.
Good a place as any to buy TV time too.