1 "Let not your heart be troubled; you believe in God, believe also in Me.
2 In My Father's house are many mansions; if it were not so, I would have told you. I go to prepare a place for you.
3 And if I go and prepare a place for you, I will come again and receive you to Myself; that where I am, there you may be also.
4 And where I go you know, and the way you know."
Facing betrayal, denial, pain, humiliation, death and separation from the Father, still Christ's main concern was for those He loves.
your (v.1) and "you" (in Luke 22:31) are plural, addressed to all the disciples.
believe (v.1) — He demands the same faith as they had in the Father. Believe in God (who is invisible). Believe in Me (who would soon be invisible). This is an exhortation to faith. In this you greatly rejoice, though now for a little while, if need be, you have been grieved by various trials, that the genuineness of your faith, being much more precious than gold that perishes, though it is tested by fire, may be found to praise, honor, and glory at the revelation of Jesus Christ, whom having not seen you love. Though now you do not see Him, yet believing, you rejoice with joy inexpressible and full of glory, receiving the end of your faith — the salvation of your souls (1 Peter 1:8).
My Father's house (v.2) temple (2:16). It was a figure of another house (Acts 7:44; Hebrews 8:5). The true tabernacle (Hebrews 8:2). Ultimately, it was heaven (Isaiah 66:1) or, in God's presence.
many (v.2) — room for all
mansions (v.2) — dwelling places (In 14:23, translated "abode)
I go to prepare a place — His death and resurrection prepared our means of access to the Father.He goes as High Priest and intercessor.
I will come again (v.3) — The rapture? (but Paul revealed that mystery). The second coming? (it doesn't seem to fit). This is probably a general statement of His future faithfulness and coming glory.
there ye may be also (v.3) — eternal communion and fellowship (john 17:24)
Our ultimate destiny is to be where Christ is. His death and resurrection prepared our way there. He is the way to that life.