Not all religions can be true, since they make mutually exclusive claims. The question is really, which truth claims are really true?
There are many reasons why Christianity can be proven to be true. Three important reasons Christians believe and trust in Jesus are:
1. What they believe comes from a reliable book. The Holy Bible is clear, consistent, and complete in recording God’s creation work, history as it has unfolded for more than six millennia, God’s redemptive plan for man, and His restoration plan for all creation. God has promised to preserve His Word and Christians trust that He has done this because He has been faithful to fulfill His promises.
2. There are historical documents and archeological finds that support the Bible’s truths. They give evidence that supports the biblical records of ancient people and their lifestyles and beliefs, ancient places, cultures, laws, and religions, the occurrence of ancient events, etc.
3. Those who have trusted in Jesus have experienced the gift of salvation from God and therefore have a relationship with God through Jesus. They are able to understand God’s teachings because the Holy Spirit reveals God’s truths to them, just as Jesus promised He would.
Yes, it’s true that Christians think the beliefs of all other religions are false. The reason is because every one is in contradiction to what the Bible teaches, and Christianity is grounded in believing God’s Word and finding hope in Jesus. Therefore, because Christians accept the Bible as the true and faithful Word of God, all other religions cannot be true.