Ok, let’s examine this.
Suppose you have been taught that “Christ” is a liar and a fraud. Now, this is not true, correct? But if you reject Christ on this basis, you aren’t rejecting the real Christ. You are rejecting a ‘made-up’ Christ.
Now, suppose that you have been taught the above. You firmly believe that the Christ you have been told of is a liar and a fraud. (Let’s say you’re a Jew or a Muslim). Now, along with this, you are also taught that God is One, that He is Savior, Father, Supreme. You’re taught the 10 commandments. You are taught to love and serve One God.
Now, all of this is TRUE. It is incomplete (lacking Christ), but it is true. And because what it teaches is true and relates to the FATHER, by definition of the Trinity, it is also related to the Son.
So even if you were taught that Christ was a liar (and you rejected this ‘made up’ Christ), you are still accepting the truth of the Father. And since you can’t separate the Father from the Son, you are accepting the REAL Christ in accepting the real Father.
So IF you live according to God’s will, even if you have rejected the ‘made up’ Christ you were mistakenly taught, in your acceptance of the true Father you are really accepting His Son and so you MAY, through God’s grace, be saved.
Does that help to explain it a bit better?