Bible Verses About Skepticism: General references

What is the Almighty, that we should serve him? and what profit should we have, if we pray unto him?

Which said unto God, Depart from us: and what can the Almighty do for them?

¶ To the chief Musician, A Psalm of David. The fool hath said in his heart, There is no God. They are corrupt, they have done abominable works, there is none that doeth good.

¶ To the chief Musician upon Mahalath, Maschil, A Psalm of David. The fool hath said in his heart, There is no God. Corrupt are they, and have done abominable iniquity: there is none that doeth good.

And it shall come to pass at that time, that I will search Jerusalem with candles, and punish the men that are settled on their lees: that say in their heart, The LORD will not do good, neither will he do evil.

Ye have said, It is vain to serve God: and what profit is it that we have kept his ordinance, and that we have walked mournfully before the LORD of hosts?