Not true. Jesus Himself said that salvation is by faith, that all that is required of men is to believe.
BJesus' commands to believe in is not simply a mental exercise. The actual Koine Greek word used nearly 100 times by St. John was "pisteuo". It means a total commitment of ones life to a complete trust in Jesus. In many of the contexts, St. John's use of the word meant to believe in spite of reasons and pressures to the contrary. As Jesus taught in the Beatitudes, belief requires actions.
Peace be with you.