Here's a thought: it is possible to be fired up about God and still be lost in sin, without Christ, and heading towards eternal destruction. Surprising? Look what Paul said in Romans 10:1-4:
"Brothers, my heart's desire and prayer to God for them (Israel) is that they may be saved. For I bear them witness that they have a zeal for God, but not according to knowledge. For, being ignorant of the righteousness of God, and seeking to establish their own, they did not submit to God's righteousness. For Christ is the end of the law for righteousness to everyone who believes." (ESV)
Here Paul is praying for his countrymen to be saved. Yet he still testifies that they "have a zeal for God." That seems contradictory. How can someone be zealous, on fire, "sold out" for God and still need to be saved? Paul tells us they are zealous for God, "but not according to knowledge." TRUTH MATTERS!
It's not enough to be fired up for God. Which God? Which Jesus? Which gospel? Are we fired up for the false Jesus who was brother to Lucifer? Zealous for the false God who only exists to make us rich? Sold out for the false gospel that doesn't command all men everywhere to repent of sin and believe on the Lord Jesus Christ?
Paul says that his countrymen were ignorant of the fact that God is giving us HIS righteousness through faith in Jesus, and so they tried to establish their own righteousness. Our good works and efforts, the total good we can muster up, is still "like a polluted garment," (Isaiah 64:6). We're simply not good enough.
This is the gospel! We are not good enough, but God IS. God is giving us HIS righteousness; clothing us with, not a polluted garment, but the glorious white robe of his righteousness: the righteousness of Christ. This is given to all who will stop trusting in their own works and put their complete trust in Jesus Christ: who he is (the sinless Son of God who became flesh), and what he has done (his work at the cross, dying for sinners and rising from the dead).
The TRUTH is indeed something to be zealous about. We need the fire. FIRE on top of TRUTH. Lord, give us both.