Sometimes I do things that would make an atheist proud. Or I say things. Or think things. Sometimes, even though I love the Lord and seek to live biblically with the Word of God as ultimate authority, I live like a practical atheist. In other words, I say God exists but I live like He doesn't. And I don't think I'm the only one.
Sometimes I live for myself and act as if morality really was up to me.
Sometimes my focus is only on the here and now, the material and the visible.
Sometimes I feel like I deserve to be happy and so I seek pleasure in the world.
Sometimes I act as if life has no bigger meaning than what directly affects me.
Sometimes I live purposelessly.
Sometimes I'm just a practical atheist.
And then I look at God. And I see His holiness, His glory, His sovereignty and His worthiness and the atheism is gone. Because I know God exists and, confronted with Him, I have no choice but to live for Him. Like a servant for the King. But it's a struggle. My flesh attempts to draw me to practical atheism, but the Spirit that lives within me convicts me and draws me to God. Paul knew this struggle well. There was a war within him.
For I know that nothing good lives in me, that is, in my flesh. For the desire to do what is good is with me but there is no ability to do it. For I do not do the good that I want to do but I practice the evil that I do not want to do. Now if I do what I do not want, I am no longer the one doing it but it is the sin that lives in me. So I discover this principle: When I want to do what is good, evil is with me. For in my inner self I joyfully agree with God's law. But I see a different law in the parts of my body waging war against the law of mind and taking me prisoner to the law of sin in the parts of my body. - Romans 7:18-23 (emphasis mine)
The battle against sin is a war, but it is a war not fought alone. Just a few verses later, at the beginning of Romans 8, Paul says,
Therefore no condemnation now exists for those in Christ Jesus, because the Spirit's law of life in Christ Jesus has set you free from the law of sin and of death. What the law could not do since it was limited by the flesh, God did. He condemned sin in the flesh by sending His own Son in flesh like ours, under sin's domain and as a sin offering, in order that the law's requirement would be accomplished in us who do not walk according to the flesh but according to the Spirit. - Romans 8:1-4
Can't you hear the joy in that? Though we still wrestle with sin, the battle has already been won! God knew we could not do it on our own, so He sent His Son "in flesh like ours" to accomplish it. So let us rejoice in the sacrifice that made us free, that released us from the "bondage of sin and corruption," from the chains of atheism, practical or not, and set us free to serve Christ, our Saviour and our God.