Then they are in error. The creeds were created by the early elders to state what a Christian MUST BELIEVE. In addition anything contrary to the creeds is heresy and all Biblical issues outside of them is to agree to disagree. This was stated by the early elders. The latter is shown by all of the different gospel preaching denominations.Before Christianity became a villain to jews, there was discussion about this among some rabbis
The Trinity would not conflict the Shema.
Im sure most Christians dont believe the trinity as it is in the creeds though.