Islam, Christianity: Only One Can Be True

The Shahada [The Islamic creed]: لَاإِلٰهَإِلَّااللهمُحَمَّدٌرَسُولُالله | lā ʾilāha ʾil ʾāllāh, muḥammadun rasūlu-llāh | “There is no god but Allah, Muhammad is the messenger of Allah [God].

vs.

Jn 17:3: And eternal life is this: to know you, the only true God, and Jesus Christ whom you have sent. [I believe in God, the Father almighty creator of heaven and earth, and in Jesus Christ, his only Son, our LORD, […] | The Apostles’ Creed]

The two creeds are irreconcilable; therefore both religions cannot both be true.

If one of them is the true Faith, the other is a corruption of it and therefore not true.