The apostle Paul describes a general Christian characteristic in Romans 10:1-3:
Brethren, my heart's desire and prayer to God for Israel is that they may be saved. For I bear them witness that they have zeal for God, but not according to knowledge. For they being ignorant of God's righteousness, and seeking to establish their own righteousness, have not submitted to the righteousness of God.
Interestingly, one of the commentators writes that "they being ignorant of" (verse 3) could be translated into "for they ignoring," which puts a totally different sense on it. When one is ignorant, he just does not know. Knowledge could have been withheld from him. On the other hand, when one ignores knowledge, the knowledge is readily available, but he turns his back on it.
A person who is self-deceived is ignoring truth rather than ignorant of it, and if that indeed is Paul's emphasis, it makes the "what is truth" question much more serious. It means that people are accountable for what they are doing, and therefore, they will pay for it to a greater extent than if they acted in ignorance.
I urge you to seek, dig and invest in discovering truth. Even MORE IMPORTANT don't ignore it...validate in through the Holy Spirit and God's word.
Opinions,commentaries and the "Google gods" all have plenty to tickle our ears with enough to build support for what we "want" to call truth. At least we can get enough to give us the latitude to justify our intent to please God (even if it is false).
I am not exempt from this statement. However, I have tested the waters of many different aspects, christ-centered religious practices, and have concluded enough to share with you what I believe to be truth.
I am always open to debate...however, I ask that you debate God about your questions and pray for me as well...all I want to receive is the truth.