Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.
Note 10 at Joh 14:6: Jesus didn't say "I am A way, A truth, and A life." He claimed to be the only way, truth, and life. No person can come to the Father except through Jesus. This means that anyone who claims to honor Jesus while advocating other ways to God, to truth, or to life besides Jesus is deceived or a deceiver.
Jesus' claims about Himself, of which this is only one, left no room for other means of salvation (Joh 10:1 and 8). He was either who He said He was or He was the greatest deceiver of all time. His own statements about Himself leave no other alternatives. Therefore, other religions that recognize Jesus and His teachings as wonderful examples but don't believe He is the only way to achieve salvation are false.
Note 11 at Joh 14:6: Jesus said later this same night, "Thy word is truth" (Joh 17:17). Jesus and God's Word are one (Joh 1:1, 14; 1Jo 5:7; and Re 19:13). Anything that doesn't agree with God's Word doesn't agree with Jesus and vice versa. In Jesus are hid all the treasures of wisdom and knowledge (Col 2:3).