These are the ones who have not defiled themselves with women, for they are celibate. These are the ones who follow the Lamb wherever He goes. These have been purchased from mankind as first fruits to God and to the Lamb. 5 And no lie was found in their mouths; they are blameless. Revelation 14:4,5. (NASB)

If the 144,000 have been redeemed from among humanity, they are certainly not blameless in the absolute sense. Because the Bible says; All have sinned and continue to fall short of the fullness of God’s glory (Rom 3:23). Their blamelessness is based on the way God relates to their record and the way they relate to each other’s records. They are “in Christ.” Justified by faith alone, without the works of the law as a means of salvation, but willing to die rather than commit a known sin.

The 144,000 are noted for their truthfulness (the opposite of Laodicea in its self-deception). No lie is found in their mouths. One of the key characteristics of God’s people at the end of time is a thorough commitment to the truth and to telling the truth in every circumstance of life. 
This is one of the ultimate goals of God’s plan of salvation. Understanding and accepting the truth is the secret to freedom and a satisfying life. This is because whatever you choose to believe will determine what you do and how you behave. The father’s name in their foreheads(v3) is the seal of His authority and ownership. “Nevertheless, the solid foundation of God stands, having this seal: ‘The Lord knows those who are His,’ and, ‘Let everyone who names the name of Christ depart from iniquity’ 2 Timothy 2:19. This is a sign, or seal, indicating that they belong to the Lord.

Wise Solomon once said, “As a man thinks in his inward parts, so is he” (Prov. 23:7). What we believe not only has a direct influence on our performance, but it has a direct influence on what we do, and how we behave. So, if there are in the world a large variety of conflicting truths, it is no wonder that the societies we live in are plagued with unrest, trouble, and strife. Jesus said, “I am the way the truth and the life.” We don’t need a way to the way, He is the way. The robe of Christ’s righteousness, with which we are clothed, has not one stitch of human devising.

God’s ultimate goal is to restore the human race to the perfection it originally enjoyed. There will be no place for error and confusion in the new earth. The problems we currently face originated with the “father of lies” (John 8:44). The solution is found in the truth as it is in Jesus (John14:6). God’s end-time people are, therefore, described as being without lies (Rev14:5), they are united in truth.