Malachi 3

You have said,
‘It is useless to serve God;
What profit is it that we have kept His ordinance,
And that we have walked as mourners
Before the Lord of hosts? v.14

Read chapter 3
It's okay to go to God in your anger and wrestle with Him of your struggles, doubts, sadness, etc.  Yet what about attitude of disrespect or selfishness in seeking God?  These Israelites hear have spoken bold harsh words to God (v.13). Yet these people loved to protest their innocence of it.  They claimed that they kept His religious commands, yet the clearly didn't as we read throughout the Old Testament, and say it hasn't profited them anything.  Their hearts said it was empty to serve God cause didn't get you anything out of it.  It was an idea, then and now, that they need to get something out of it, if not why bother serving God.  Believing in God isn't just a safety get out of jail (hell) free card, like a back up plan in case eternity with Jesus really is true.  Choosing to follow Jesus in this life isn't because everyone's doing it or because God will give you everything you ever wanted. Believing and following Jesus is because we realize we were created for Him and His glory and without it we are empty and everything is vain.
As we serve God, lives start to change and that is worth more than money can buy. Someday we'll see that the Lord saw and remembered as we are given the hope in verse sixteen, "Then those who feared the Lord spoke to one another,
And the Lord listened and heard them;
So a book of remembrance was written before Him
For those who fear the Lord
And who meditate on His name."Why do you choose to serve and follow God?  Is it to get something out of it?  How has that idea failed you?