Jesus said, "I am the way, the truth and the life, no man can come unto the Father but by Me."
That sounds pretty EXCLUSIVE to me. God has also said in the OT He is a jealous God and we are not to put any other gods before Him. We are told to go out and preach the good news of the gospel to the world which is Jesus Christ and Him only for He is the only one that shed blood for the atonement of sinners.
We are not to approve of others if they are worshipping some other god by telling people of all faiths that all roads lead to heaven. That is ecumenical and totally untrue if you are a bible believer and believe what God's word plainly teachs. Jesus said, "Narrow is the way and few there be that find it! We can't convert or save anyone, that is God's part, but we need to tell lost people the whole truth!