It is true many religions have similar teachings but it were all the same, it would not have been called by different names.
In fact, underneath the surface, there are many differences. For example, Buddhism tells you that you can attain godhood. The Bible teaches there is only one God, the creator of the universe. Islam tells you Jesus is only a human prophet. The Bible says Jesus is God Himself dwelling in flesh on earth. Some religions will tell you to do good deeds to earn your salvation. The Bible teaches we can never match up to the standard of a perfectly holy God and needs to put ourselves entirely at His mercy.
There are so many different religions. Why are you so sure Christianity is the only way to God?
Christianity is unique because evidence supports the fact that the Bible is the Word of God.
Not only is the Bible unique, the person Jesus Christ is also unique. Many founders of religion taught many things while they were alive. But when they died, they remain dead. How do we know whether what they teach is true and whether they are who they claim to be? Jesus Christ is unique because by resurrecting from the dead He has substantiated His claims to be the Son of God.