Think intently and at length, as for spiritual purposes
Contemplate
Study
Cogitate
Think
Cerebrate
Meditation
Meditative
Reflect deeply on a subject
Chew over
Excogitate
Mull
Mull over
Muse
Ponder
Reflect
Ruminate
Speculate
Think over
Wonder
Theologise
Theologize
Bethink
Consider
Introspect
Premeditate
Puzzle
Question