As a Christian all my life I never heard anyone say the doctrine of the trinity is taught in the Bible; anyone who believes that shows they haven't been reading their Bible. Now, if one were to say, the concept of the trinity is in the Bible, a case can be made for that. Nowhere does the Bible encourage us to teach on the trinity or God's tri unity. As Christians, we know God is one with no associates or partners, and Jesus is His word. He is the word God used to create all things.We are taught God is Spirit and He Holy; therefore, He is the Holy Spirit.
Everyone and anyone who tries to explain the trinity always falls short. Even Allah or Muhammad imply a trinity that they impute to Christians that which was never accepted by Christianity such as Allah (or the father God) being the third of three and Mary being God or part of the trinity. I say leave topic alone, bc God is past finding out and He is not like any thing of this earth that we could explain. The trinity concept is other worldly and cannot b explained by infinite human beings, but just because we cannot explain some thing, that is not a reason to reject the concept