the holy trinity

[all4salam]

i was having a discussion with someone about the nature of jesus(PBUH). as a muslim, we are taught in the qur'an, that allah is one. they were telling me how god is one with three co-equal parts. well this goes against tawheed and the ot. my question is to christians, how could this be when there is no mention of this in the ot? not only that, there are countless passages where jesus (PBUH) gives glory and praise to the father. do you ignore these passages as they conflict with the trinity doctine? SALAM