There are many who say truth is relative. If one does not accept God, His Word, or His Son then it is true that truth is indeed relative. If God is not the measure of truth, then there is no one truth. If truth is measured by man, there are as many truths as there are men. One is just as valid as another.
Ignoring God and His Truth does not diminish either. The only one diminished is the one that chooses his or her own way.
If one believes in God, His Word, and His Son then for that person there is one Truth for all men. This becomes the measure of the one who calls himself or herself a Christian. If you don’t believe Christ then you are not a Christian. If you don’t believe what He taught and follow His commandments you are not a Christian. If that is the case, calling yourself a Christian is a self deception and can only cause confusion for those who are earnestly seeking the Truth. Your truth should invoke a name that reflects more closely your belief and its source. There are many to choose from and it is in vogue to create your own version.
God has provided the way to find Him. Any other path taken is as useful and useless as another. This is what the Bible says, the Word of God. It is the Lord Jesus Who calls out in truth and love:
Come to Me