Blasphemy or Superstition?

From your description, it does not sound to me like what you have done qualifies as blasphemy. To be honest, it sounds more like you have a superstitious view of blasphemy of the Holy Spirit, and that your worry is biblically unwarranted. There are two ways to approach the question of blasphemy, and I'll try to hit on both of them.

First, we can look at the biblical definition of blasphemy. Blasphemy in general is "speaking against." "Speaking" is pretty self-evident, although by implication we should also include other forms of public discourse like writing. "Against," however, is a fairly vague term. In this case, it refers to taking a position in opposition to that of which one speaks. To speak against God is to say things in opposition to God himself, not merely against what God says. So, bad theology is not equivalent blasphemy. Blasphemy refers instead to things like calling God a liar, or cursing or reviling him (e.g. Ex. 22:28). It may be direct, such as in saying evil things about God, or indirect, such as in making claims that cannot be true unless evil things are true about God. For instance, in Matthew 9 some people considered Jesus to have blasphemed when he assumed for himself the power to forgive sins. Jesus essentially claimed equality with God. And this would have been an indirect form of blasphemy had it not been true.

But in all cases, motive and meaning are important. One does not speak against something unless one's meaning attacks that something, regardless of what words one uses (cf. A Lie is an Abomination unto the Lord ...). Words convey meaning only according to their actual or perceived intention (cf. Matt. 22:15-18). Since God always perceives accurately, his perceptions always precisely match your intentions (1 Chr. 28:9). And speaking against God is not blasphemy if it is not intended to defame him and motivated by defiance against him (Num. 15:21).

We see a parallel to this idea in the laws regarding murder and manslaughter. The difference between these two actions is not in their outward appearance but in the intentions behind them (Ex. 21:12-14; Num. 35; Josh. 20). The same idea applies in many other cases in Scripture, as well (Num. 15:22-31; 2 Chr. 30:18-20). Simply put, the outward appearance of things is not the only factor in determining when things are right or wrong. Actions must be considered in their totality, and judged accordingly. Sometimes things that are sinful in one setting and with one motive, are not sinful when the setting and/or motive is changed.

With regard to a joke, a joke that does not mean anything harmful toward God, and that does not accomplish harm against him, should usually be considered harmless and not sinful. Making God the butt of a joke is sometimes inappropriate and sinful (though it also may be acceptable), but even when it is sinful it is not necessarily blasphemous. For instance, when a man was caught cursing God in Leviticus 24, he was not summarily executed. On the contrary, Moses was not able to render a judgment based on his knowledge of what the man had done. Instead, he appealed to God for his judgment on the matter. As it turned out, the man was executed. But the fact is that it could have gone either way. The details Moses was given were insufficient to render a judgment on the matter, even though Moses knew what the man had said.

So, if you made jokes about God because you hate him, then you blasphemed him. But if you merely made jokes that involved references to God because you saw something humorous in his creation that reminded you of true things about God, then you certainly did not blaspheme him.

The second way to approach the question of blasphemy is to look at the fact that blasphemy of the Holy Spirit is unforgivable. Now, it is important to distinguish the Holy Spirit from the Father and the Son in this regard, since blasphemies against the Father and Son are forgivable (Matt. 12:31-32). Only unbelievers may blaspheme the Holy Spirit, but believers may blaspheme the Father or Son (and be forgiven). Therefore, if you are a believer, you have not blasphemed the Holy Spirit.

Scripture has far more to say about what it takes to be a believer than it does about what it takes to blaspheme the Holy Spirit. Therefore, a very good way to approach this question is to look at what a believer is. If you believe the gospel and love God, then it is impossible that you have blasphemed the Holy Spirit. If you think you have, then you have simply misunderstood the Bible's teaching regarding the definition of blasphemy of the Holy Spirit.

I mentioned in the beginning that your worry sounded superstitious. A superstition is a belief that depends less on reasoning and more on fear and lack of knowledge. In the case of blasphemy of the Holy Spirit, there is much superstition in the church. People who worry about blaspheming the Holy Spirit are almost always fearful of the consequences of it, but equally often they cannot provide a clear, scriptural argument demonstrating why their actions are blasphemous. Because the teaching of Scripture on this topic is rather vague, those who are prone to be less secure in their understanding of their salvation tend to imagine that its definition is quite broad, such that anything that sounds remotely like blasphemy gets lumped under the category of blasphemy. And in fact, many, many Christians worry about this.

But this is the wrong approach. Our reliance on Scripture ought to encourage us not to condemn anyone without proper scriptural backing. The less clearly Scripture speaks to a subject, the less ready we should be to condemn anyone on the basis of what Scripture says. The more vague Scripture's teaching on blasphemy of the Holy Spirit is, the more we should refrain from accusing anyone of it, including ourselves. Of course, I think Scripture is not entirely unclear about this subject, and that what you had done does not qualify. But if you think I'm wrong about its clarity on the issue, your response should still be to worry less.

In any event, in the one scriptural example of blasphemy of the Holy Spirit (Matt. 12 // Mark 3 // Luke 12), Jesus directs his words against those who outwardly reject him and his gospel. If blasphemy of the Holy Spirit were a widespread phenomenon among believers, then Scripture should have addressed it more often and in the context of believers. Instead, Scripture spends its time speaking against those in the church and outside the church who purposefully and knowingly reject Jesus and/or the teachings of Scripture on more central issues like the gospel. Jesus' teaching on blasphemy of the Holy Spirit was not intended as a warning against those who love him and seek to do his will, but against those whose outward opposition to him is so great that they reject not only him and his testimony, but also the works of the Holy Spirit that testify that Jesus is the Son of God.