Monotheists, how do you know there is only one god?

After many discussions here in which monotheists cited what they deemed convincing evidence for the existence of their particular god, it strikes me that the same type of texts and believer experiences they cite as proof of their deity’s existence apply just as well to other creator deities. Whether it be Yahweh, Father-Son-Spirit, Allah, Brahma-Vishnu-Maheshwara, Shangdi, Pangu, The Great Spirit, Ik Onkar, The Baha’i All-Powerful, Mbombo, Unkulunkulu, Nanabozho, Coatlicue, Viracocha, or the Inuit Raven; they all seem about equally probable. They are all supported in holy texts or verbal traditions from the distant past. Their believers all share similar anecdotal evidence for their existence; including actual sightings, voices heard, prayers answered, and miracles performed. Why do you think your god is better than the other guy’s god? If the claims for each have similarly equal validity, and you believe those claims justify your faith in your particular one, why not accept all of them?