By following three very different religions Pi is trying to state that it is not what religion you belong to but how spiritually content you are is important. To say that Pi attracts religions like a dog attracts fleas is the opposite of what he believes he is achieving by practicing Islam, Hinduism, and Christianity at the same time. He is simply trying to grasp what one religion is teaching by looking for answers in another. When Pis parents and religious leaders criticize him for having multiple religions, they are being close minded and critical, which is exactly what his three religions are not about. This further justifies his multiple religious practices. He is also trying to show that the first religion you are introduced to is not always the best suited to you and it is worth exploring your options. By doing something that is considered slightly sacrilegious he demonstrates that exploring your options, even if it is three religions at once, will leave you more spiritually content.