Today's first reading from Deuteronomy ends with:
You shall therefore carefully observe the commandments, the statutes and the decrees that I enjoin on you today.”
We often talk about the commandments, but I can't remember the last time I heard someone even acknowledge that there are statutes and decrees.
I had to go back myself and look at what the rabbis wrote to understand the distinction. They are all laws but different kinds of law.
Commandments would fall into the category we would think of as natural law. They are common sense. They are laws that prohibit murder, robbery, slander, perjury, adultery,etc.
The decrees, sometimes translated ordinances, are the ritual rules like the ones we have in the Church for how one is to baptize, with water in the name of the Father and of the Son and of the Holy Spirit.
The tough group are the statues. The statues are those laws "whose purpose has not been revealed to us." Does God have a reason for them? Yes. Has he told us what the reason is? No.
We simply have to trust. Here is where we have a hard time. Our natural tendency is that any rule that doesn't make sense to us is silly and we act as if we have the right to dismiss it.
We can now look back and understand perfectly well why God told the people of Israel to wash dishes, or to not mix dairy a meat products. But there are other laws even in the New Testament we may still not fully understand.
Yes our Christian faith is reasonable. That is, we can use our intellect to search for a deeper understanding. But humility requires that we recognize the limits of our human understanding. How many time in our history have we done things that at the time we believed were a good idea, only to discover that the complexity of the situation was far beyond us, and we had made a mistake? In our hubris we made a situation worse.
Do some of God's laws seem unreasonable? Yes. But rather that simply rejecting what God has taught us through the Bible and continues to teach us through his Church, we should let our lack of understanding lead us to study more, pray more, and most of all trust more.