'According to my judgment the most important point to be attended to is this: above all things see to it that your souls are happy in the Lord. Other things may press upon you, the Lord's work may even have urgent claims upon your attention, but I deliberately repeat, it is of supreme and paramount importance that you should seek above all things to have your souls truly happy in God Himself!' - George Mueller
Doesn't it sound selfish to make yourself happy in God? Surely that's just using God to make you happy? Below is the reasoning that forces me to believe (like George Mueller) this it is essential to make myself happy in God:
1) The chief purpose of the Christian Life is to glorify God. (1 Cor 10v31)
2) When sinners are born-again they receive a new heart. ( Ezekiel 36v26)
3) The heart's function is to produce desires. (Psalm 37v4b)
4) The new heart (given by God) produces spiritual desires or desires rooted in the Holy Spirit.
5) To be happy is to fulfill desires and cravings. The greatest measure of happiness happens all desires are fulfilled.
6) To be happy in God is to fulfill Spiritual desires from the new heart.
7) Holy-Spirit desires are given so that the fulfilment of them glorifies God. (God does all things for His own glory).
8) By implication of 6) and 7) we must make ourselves happy in God (fulfilling Spiritual desires) because this glorifies Him.
Three Misconceptions about Happiness:
1) I can't be 'happy in God' all the time because sorrow is a good emotion that God wants me to experience (2 Cor 7v10).
This misconception assumes that humans exert one emotion at a time. The truth is we can be happy and sorrowful simultaneously. 2 Cor 6v10: 'sorrowful yet always rejoicing'. A happiness in God can happen when we are filled with sadness.
2) Happiness is given by God sometimes and other times not. It is not to be pursued. It's to be accepted if God chooses to let me enjoy it.
If this is true why did Paul command the Philippians several times to 'Rejoice in the Lord' (Phil 4v4). Not rejoicing is a sin. Getting joy in God is commanded therefore it is our obligation and duty.
3) Pursuing your own Happiness is living by feelings and not faith.
Faith and feelings are not independent of each other. The right faith tends to produce the right feelings (Rom 15v13).
'God is glorified not only by His glory's being seen, but by its being rejoiced in.' -Jonathon Edwards