A body posture that can signify an attitude of adoration, respect, reverence and submission in worship or prayer (1 Kgs 19:18; 2 Kgs 1:13; Act 7:60; 20:36).
The psalmist, said let us kneel down in worship before God (Ps 95:6). Daniel and Paul got down on their knees and prayed (Dan 6:10; Eph 3:14). In the garden just prior to His arrest and crucifixion Jesus knelt down and prayed (Lk 22:41). However, the inner attitude of heart is more important than any outer stance of the body.
Ultimately, Christ’s universal Lordship will be acknowledged by every knee bowing to Him and giving Him praise (Rom 14:11; Phil 2:10,11). While this is a recognition of His justice and supremacy it will not result in the eternal salvation of those who are not believers.