Jesus Christ is the same yesterday and today and forever (Heb 13:8 NRSV)
This verse is often used against LDS theology; critics sometimes cite this verse as "proof" against the LDS view that Jesus' eternal nature of an intelligence took on the form of a spirit son of God (the Father) (assuming the idea of "spirit birth") and that His glory and divinity is static.
Firstly, it should be noted that this is not what is in view in this passage; as one conservative Evangelical commentary stated:
v 8 is not to be interpreted as an acclamation of Jesus' timeless ontological immutability, corresponding to the assertion that the Son remains ὁ αὐτός, "the same," in 1:10–12 (as asserted by H. Montefiore, 242; P. R. Jones, RevExp 82 [1985] 400; cf. Grässer, Glaube, 23; Buchanan, 233). The reference is rather to the immutability of the gospel message proclaimed by the deceased leaders in the recent past (see Michel, 490 and n. 2; P. E. Hughes, 570–71). Although the preachers change, the preaching must remain the same. The unchangeableness of the revelation is a consequence of the transcendent dignity of Jesus Christ, the originator of the preaching (2:3) (so Thurén, Lobopfer, 183). (William L. Lane, Hebrews 9-13 [Word Biblical Commentary 47B])
On biblical (and Book of Mormon) texts on God being eternal and unchangeable, see my fuller discussion here.
Indeed, Heb 13:8 cannot be a statement of metaphysical natures of Jesus not being changed; if such were the case, this would contradict the claim that Jesus Christ emptied himself to become a man like us (cf. Heb 2:16-18; 4:15). Consider the following from Phil 2:5-11 (NRSV):
Let the same mind be in you that was in Christ Jesus, who, though he was in the form of God, did not regard equality with God as something to be exploited, but emptied himself taking the form of a slave, being born in human likeness. And being found in human form, he humbled himself and became obedient to the point of death--even death on a cross. Therefore God also highly exalted him and gave him the name that is above every name, so that at the name of Jesus every knee should bend, in heaven and on earth and under the earth, and every tongue should confess that Jesus Christ is Lord, to the glory of God the Father.
Notice that Christ (viewed in the totality of His person; Paul is not speaking merely of his human nature) has been exalted after His ascension, and only then was He given the name above all other names (v.9). This is commensurate with LDS Christology (cf. D&C 93:1-20), but inconsistent with the Hypostatic Union. For a fuller discussion, see my paper responding to Bobby Gilpin on LDS Christology.
When all things are considered, Heb 13:8 is not a valid “proof-text” against LDS theology.