There are many religions claiming to have the truth about how we relate to God. Though they all evidently have some truth, they do, in fact, make contradictory claims, so they can’t all be entirely true. How do we know which one is true? How do we know if any of them are true? How should we evaluate their truth claims? How do we know when we have finally found the truth?
To coherently evaluate truth claims we must evaluate evidence for and against each claim, assuming truth claims cannot contradict or be inconsistent with each other.
We should also perceive from the very existence of multiple, contradicting religions, as well as from the evil apparent in the world, the existence of a lying personality, a spiritual Deceiver determined to mislead us, and expect it to be very convincing. In other words, our search for truth requires honesty and rigor; we must lay aside our bias; we must be thorough and relentless.
A useful device in any pursuit of truth is proof by contradiction: when assuming a truth claim is false leads to contradiction, we prove the claim is true.
For example, assuming there is no god implies abiogenesis: that life randomly sprang from non-life, and that the universe spontaneously created itself ex-nihilo, from nothing. Both implications contradict basic, well-established science; therefore, there is a god: both atheism and agnosticism are irrational, invalid world views.
The next natural step is historical; examine the most verifiable fact of all human history: the Resurrection of Jesus Christ. Assuming Christ did not rise from the dead implies every single one of His twelve apostles suffered immensely for what they knew was a lie without expecting any earthly benefit; not one of them ever recanted, even under extreme torture. This contradicts human nature on a very basic level. This proves Jesus Christ did rise from the dead.
The next reasonable step is a literary one: examine the reliability of the Bible. Assuming the Bible is unreliable contradicts Christ Himself; atheists (e.g. Bart Erhman) admit historical records of Christ’s beliefs are reliably preserved for us in the four Gospels, which document Christ’s implicit trust in the Tanakh (the Hebrew scriptures) as the inspired Word of God. (Jn 10:35, Lk 16:31) The testimony of Jesus Christ is all we need: we may safely trust the Tanakh; its claims are more reliable than any supernatural sign we might encounter. (2Pe 2:19-21)
So, we may conclude that any religion which does not align with both the Resurrection of Jesus Christ and the Tanakh is a lie, the work of the Deceiver. Let’s cross-check and verify this, testing each world religion for consistency.
Assuming Islam is false leads to no contradiction: Muhammed could plausibly have been assisted by the Deceiver; he benefited immensely from his own propaganda and his message conveniently evolved over time to suit his ends.
Similarly, assuming Hinduism is false leads to no contradiction; oral tradition and idolatry mixed with supernatural visions and experiences aided by the Deceiver is certainly plausible.
Assuming Buddhism is false leads to no contradiction; an ancient eastern philosopher got some basic things wrong. Not an issue.
Assuming Judaism is false leads to no contradiction; though He rose from the dead, they continue to reject their own Messiah, presuming they can cover their sins through ritual and tradition, which is inconsistent with the Tanakh. (Eze 18:4) No contradiction here.
Surprisingly, assuming Christianity itself is false also leads to no contradiction; claims that Christ abolished Torah (the supposed civil / ceremonial parts) evidently emerged in the mid-second century in response to Fiscus Judaicus to create a new religion distinct from the Torah-centered apostolic faith, presenting another Jesus which Christ’s Apostles would not have recognized. Its rejection of Mosaic Law as the standard by which we define sin (1Jn 3:4) exposes Christianity as an insidious, elaborate counterfeit, another work of the Deceiver.
Where does this rigorous search for truth inevitably lead us? to search the Tanakh to find peace with God (Jn 5:39) using the New Testament as a guide with the Tanakh as our foundation; we must be very careful since Christianity consistently misinterprets the Apostle Paul to wrest much of scripture in one way or another, especially in this area. (2Pe 3:16)
As we search scripture, we find we are all sinners in need of salvation (Ps 14:2-3); we have all broken Torah and are at enmity with God as a result, deserving of spiritual death. (Eze 18:4)
God has made a way for us to be reconciled with Him through faith in Messiah (Ha 2:4), trusting Jesus Christ to take our place and die for us, being punished for our sin. (Is 53:6, 11)
God imputes perfect righteousness to all who believe in God as our atonement for sin through Jesus Christ. (Ge 15:6) He imparts spiritual life into us (Ps 119:140), gives us a new heart, writes His Torah into our hearts, forgives us of all of our sins against Himself, and enables us to obey and love Him. (Je 31:33-34)
The witness of the Tanakh echoes the call of Jesus Christ to every one of us, “Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life.” (Jn 5:24) This is how we are reconciled to God; this is the way of salvation. There is no other. Ask and we receive, seek and we find, knock and God will open the door for us. Mt 7:7-8