That group is a "binitarian" one which means they only accept two Persons in God. They also have a silly notion about divinization which affirms that we can all become just as "god-like" as God Himself.
A portion of that group separated to affirm a Trinitarian confession etc.
My father used to read the "Plain Truth" for its "predictions" of world events.
Just don't read their literature and don't watch their programming.
And if one does that, and is not sufficiently grounded in his or her faith, then, yes, doubt will be sown.
I knew a Catholic couple who were both Catholic school teachers. They once invited Jehovah's Witnesses to come into their home to debate them. The wife actually went on to join them . . .
Alex