Some say that Christians believe they are the only ones who will be saved. Before I became a Christian, that was the belief of the denomination I was in; only those in my denomination would be in heaven. Everyone else was just rolling the dice, betting on God's good graces to get into heaven. That was not a bet I was willing to make though. The odds are no good; it is a 50-50 proposition even if you completely throw out all of the evidence supporting God and the Bible. There either is a God or there isn't. If there isn't, then none of this makes any difference. If there is, then He either said the things He said in the Bible or He didn't. If He didn't, then we have no idea what He wants of us, if anything, and so it would make no difference if He existed or not. If He did say the things in the Bible, then we need to know about them or face some pretty dire consequences.

Acts 17:22-31

22 Then Paul stood in the midst of the Areopagus and said, "Men of Athens, I perceive that in all things you are very religious; ²³for as I was passing through and considering the objects of your worship, I even found an altar with this inscription: TO THE UNKNOWN GOD.
Therefore, the One whom you worship without knowing, Him I proclaim to you: ²⁴God, who made the world and everything in it, since He is Lord of heaven and earth, does not dwell in temples made with hands. ²⁵Nor is He worshiped with men's hands, as though He needed anything, since He gives to all life, breath, and all things. ²⁶And He has made from one blood every nation of men to dwell on all the face of the earth, and has determined their preappointed times and the boundaries of their dwellings, ²⁷so that they should seek the Lord, in the hope that they might grope for Him and find Him, though He is not far from each one of us; ²⁸for in Him we live and move and have our being, as also some of your own poets have said, "For we are also His offspring.' ²⁹Therefore, since we are the offspring of God, we ought not to think that the Divine Nature is like gold or silver or stone, something shaped by art and man's devising. ³⁰Truly, these times of ignorance God overlooked, but now commands all men everywhere to repent, ³¹because He has appointed a day on which He will judge the world in righteousness by the Man whom He has ordained. He has given assurance of this to all by raising Him from the dead."

Clearly, we need to seek out the Lord and join in His church. In order to do that, we need to know what that church is. Lets look at what the Bible says about the church

Ephesians 4:1-6

I, therefore, the prisoner of the Lord, beseech you to walk worthy of the calling with which you were called, ²with all lowliness and gentleness, with longsuffering, bearing with one another in love, ³endeavoring to keep the unity of the Spirit in the bond of peace. ⁴There is one body and one Spirit, just as you were called in one hope of your calling; ⁵one Lord, one faith, one baptism; ⁶one God and Father of all, who is above all, and through all, and in you all.

Is this exclusionary as some claim? Worldly knowledge would say so. For how can a Buddhist, or a Muslim, or a Catholic be saved if there is only one faith? You are exclude from God's church only if you choose not to answer His call and not obey what He asks you to do. God provides the increase in His church, the church found in His word What is His church? Jesus Christ is His church"

Ephesians 1:17-23

17that the God of our Lord Jesus Christ, the Father of glory, may give to you the spirit of wisdom and revelation in the knowledge of Him, ¹⁸the eyes of your understanding being enlightened; that you may know what is the hope of His calling, what are the riches of the glory of His inheritance in the saints, ¹⁹and what is the exceeding greatness of His power toward us who believe, according to the working of His mighty power ²⁰which He worked in Christ when He raised Him from the dead and seated Him at His right hand in the heavenly places, ²¹far above all principality and power and might and dominion, and every name that is named, not only in this age but also in that which is to come.
²²And He put all things under His feet, and gave Him to be head over all things to the church, ²³which is His body, the fullness of Him who fills all in all.

God wants all people everywhere to be in His church (1 Timothy 2:4). That is why He sent Jesus to establish His church and to pave the way to salvation. It is not God who excludes us but we who exclude God. And How do we exclude God? When we do not obey His word. His word is salvation (Romans 1:16). The gospel is God speaking to each and every one of us through inspired writers. It will show the path to eternity with Him to those who believe it. It is His unchanging guidebook. It is we who change the one faith or the one baptism or the one spirit to our own ends. It is we who change ourselves to meet our individual needs and desires. Unfortunately, this is not new:

1 Corinthians 1:10-15

10 Now I plead with you, brethren, by the name of our Lord Jesus Christ, that you all speak the same thing, and that there be no divisions among you, but that you be perfectly joined together in the same mind and in the same judgment. ¹¹For it has been declared to me concerning you, my brethren, by those of Chloe's household, that there are contentions among you. ¹²Now I say this, that each of you says, "I am of Paul," or "I am of Apollos," or "I am of Cephas," or "I am of Christ." ¹³Is Christ divided? Was Paul crucified for you? Or were you baptized in the name of Paul?
¹⁴I thank God that I baptized none of you except Crispus and Gaius, ¹⁵lest anyone should say that I had baptized in my own name.

Let's replace the names in this passage with modern divisions to help us realize God's wisdom:

Now I say this, that each of you says, "I am a Lutheran," or "I am a Baptist," or "I am a Catholic," or "I am of Christ." Is Christ divided? Was Luther crucified for you? Or were you baptized in the name of the pope?

God clearly pleads with all His creation to speak with one voice, the voice of Jesus; the voice as we hear it in His gospel. How can we speak with Jesus' voice? How can we join His church, the one church we read about in the Bible? For we are assured that there is only one church by the very Spirit of God as found in His word. Obey that gospel. It’s as simple as that.