hello Nathan, dirtfarmer here
What does it mean "to confess with your mouth and believe in your heart"? Romans 10:9-10, " That if thou shalt confess with thy mouth the Lord Jesus Christ and believe in thine heart that God hath raised him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation." In Luke we have an example: Luke 18;13-14 " And the publican, standing afar off, would not lift up so much as his eyes unto heaven, but smote upon his breast, saying, God be merciful to me a sinner. I tell you, this man went down to his house justified rather than the other: for every one that exalteth himself shall be abased; and he that humbleth himself shall be exalted."
2 Corinthians 5:17, " Therefore is any man be in Christ he is a new creature; old things are passed away; behold all things are become new." What are the "old things" and what does "are passed away" mean?
Salvation comes while were are still sinners according to Romans 5:8, " But God commendeth his love toward us, in that while we were yet sinners, Christ died for us."
When we believe in our heart that Christ died for us were are made a new creature. In order to be made new the old has to pass away; it is not a "remodeling" job; we are created in Christ Jesus for good works, because of salvation, not because of anything that we do.
You really pose good questions, I like that you think about things.
To confess with the mouth, means you really believe in your heart.
Luke 6:45 (ESV)
The good person out of the good treasure of his heart produces good, and the evil person out of his evil treasure produces evil, for out of the abundance of the heart his mouth speaks.
If a person did not really believe, then they would not truly confess.
The old things that have passed away is the slavery to sin, and all that it requires us to do.
Ephesians 4
17 Now this I say and testify in the Lord, that you must no longer walk as the Gentiles do, in the futility of their minds.
18 They are darkened in their understanding, alienated from the life of God because of the ignorance that is in them, due to their hardness of heart.
19 They have become callous and have given themselves up to sensuality, greedy to practice every kind of impurity.
20 But that is not the way you learned Christ!-
21 assuming that you have heard about him and were taught in him, as the truth is in Jesus,
22 to put off your old self, which belongs to your former manner of life and is corrupt through deceitful desires,
23 and to be renewed in the spirit of your minds,
24 and to put on the new self, created after the likeness of God in true righteousness and holiness.
Our new creation is in Christ, but that does not mean the old man and the world do not still try and lead us away. Gods seed is in us who believe, and just like a seed grows into a plant, so too God word grows in us.
We see that those who's soil is less than perfect, who's heart is not being 'worked' for the plant to grow, the plant can become dead due to heat and choked due to other things growing with it - so too the word of God will die if there is no depth of root or because of other desires in our heart.
We are soil, He is the farmer. We can't change our hearts but He can - and will if we submit. We simply need to abide in Him.
John 15:4 (ESV)
Abide in me, and I in you. As the branch cannot bear fruit by itself, unless it abides in the vine, neither can you, unless you abide in me.