“You have loved righteousness and hated wickedness; therefore God, your God, has set you above your companions by anointing you with the oil of joy.”
Hebrews 1:9 (New International Version)
Holiness and true happiness are inseparably connected. If you remain pure in your thoughts and deeds and remain faithful to God, you will feel connected to Him-the source of true happiness. But the moment we entangle ourselves in worldly matters, the connection with our Lord God gets broken and we start to feel miserable. To the extent you choose to be holy is the extent to which you will be happy. Conversely, to the extent you compromise holiness is the extent to which you diminish happiness. It’s just that simple.