The tribulation is not the context.
Chapter 6 begins with “Therefore,” which means the author is building a doctrine from the previous chapter, 5. Begin there and you will see he is speaking of “immature” beliverers (jews). He goes on to chastise them for their lack of understanding but ends with the surety of God pictured as being an anchor for our soul, one who keeps His promises.
So in actuality it is a warning that each of us need to “live” out our faith, that is the same message James extolls. Nothing whatsoever is alluding to the tribulation. It goes on to speak that God keeps His promises, and it speaks to
His faithfulness, not ours!
16For men verily swear by the greater: and an oath for confirmation
is to them an end of all strife.
17Wherein God, willing more abundantly to shew unto the heirs of promise the immutability of his counsel, confirmed it by an oath: 18That by two immutable things, in which
it was impossible for God to lie, we might have a strong consolation,
who have fled for refuge to
lay hold upon the hope set before us:
19Which
hope we have as an anchor of the soul, both
sure and stedfast, and which entereth into that within the veil(
Jesus);
20Whither the forerunner is for us entered,
even Jesus, made an high priest for ever after the order of Melchisedec.