How crucial is it for Christians in general (not only LDS) to “gain a testimony” validating the truth of their beliefs?

The idea of “**gaining a testimony**” is a key aspect of Latter-day Saint teachings, suggesting a special kind of revelatory spiritual experience serving to establish the truth of specific doctrines. Consequently, this experience is meant to possess remarkable epistemological significance. > **A testimony is a spiritual witness given by the Holy Ghost**. We can **gain a testimony** that we are children of our Heavenly Father, and that he loves us. We can **gain a testimony** that Jesus Christ is our Savior, and because of Him, our sins can be forgiven. We can **gain a testimony** that Joseph Smith was a prophet of God, and that the Church of Jesus Christ of Latter-day Saints is Jesus Christ’s restored church on the earth today. **By the power of the Holy Ghost, we can know the truthfulness of these things**. We can share our testimonies with others. > >(Source: [I Know This Church is True](https://www.livingscriptures.com/fhe-lesson-i-know-this-church-is-true-3/)) > **How Can I Gain a Testimony?** > > The most important truth you can learn is that the gospel of Jesus > Christ is true. This knowledge is called a testimony. You can have a > testimony, but it takes work. [...] > > - Read and study the scriptures. > - Obey Heavenly Father’s commandments. > - Attend sacrament meeting and Primary. > - Pray in faith to Heavenly Father **for a testimony** that the gospel of Jesus Christ is true. **You will know it is true “by the power of the** > **Holy Ghost”** (Moro. 10:5). > >(Source: [How Can I Gain a Testimony?](https://www.churchofjesuschrist.org/study/friend/2005/11/how-can-i-gain-a-testimony?lang=eng)) > [...] Earlier that month, one of my friends who had also been investigating The Church of Jesus Christ of Latter-day Saints **received revelation that the Church was true**. I’m not going to lie, I was incredibly happy for him, but a part of me was slightly jealous when I found out. I had been reading the Book of Mormon and praying diligently almost all summer, asking God if this church was true. I was ready to join, ready to convert, ready to take it all in…. **once Christ gave me a sign**. **I had not received my green light yet**, so I sat on the edge of believing and wanting to be a part of this church without committing to a baptism. **I had to know that Christ wanted it for me**. **Without some sort of sign or answer from Him, I was not willing to become a member**. > > (Source: [The Effort to Gain a Testimony](https://ldsblogs.com/43275/the-effort-to-gain-a-testimony)) > This is the true, solid evidence of religious faith. Millions upon millions of Latter-Day Saints attest to the power of this principle: when you go to God in prayer, asking if this thing that purports to be from Him is true, *he does answer*. **It is a distinctive and unmistakable experience, and once you have received a confirmation of the truth from God, any earthly evidence pales by comparison. People can make mistakes, but the witness of the Holy Ghost is powerful and absolute**. > > (Source: [According to Latter-day Saints, should every honest, rational, and well-informed individual be able to reach the conclusion that Mormonism is true?](https://christianity.stackexchange.com/a/99550/61679)) Does the notion of "**gaining a testimony**", perhaps worded in different terms, exist universally across Christianity? Is this something important for all (or at least most) Christian denominations or just for Latter-day Saints?