You ask how a carnal man can get saved — a question prompted by your reading of Romans 8:5-8. God offers the gift of salvation to those who
- believe the Gospel
- repent and turn from their evil ways then are baptised into Jesus Christ
- obey God and Jesus and strive everyday to serve them, leaving the things of the flesh behind
Some verses to elaborate the points above:
Acts 8:12 But when they believed Philip as he preached good news about the kingdom of God and the name of Jesus Christ, they were baptized, both men and women.
The words “good news” are equivalent to the word gospel. So as those who believed Philip, we also have to understand and believe the things concerning the kingdom of God and the name of Jesus Christ.
Acts 17:30-31 The times of ignorance God overlooked, but now he commands all people everywhere to repent, (31) because he has fixed a day on which he will judge the world in righteousness by a man whom he has appointed; and of this he has given assurance to all by raising him from the dead.”
Repentance is vital. We have to change the way we think from thinking in a carnal manner to thinking in a spiritual manner.
Mark 16:16 Whoever believes and is baptized will be saved, but whoever does not believe will be condemned.
The above verse shows clearly two very important requirements to be saved.
The following section from Romans, tells us the process we must go through, in our conversion from being carnal to being spiritual.
Romans 6:3-13 Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? (4) We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life. (5) For if we have been united with him in a death like his, we shall certainly be united with him in a resurrection like his. (6) We know that our old self was crucified with him in order that the body of sin might be brought to nothing, so that we would no longer be enslaved to sin. (7) For one who has died has been set free from sin. (8) Now if we have died with Christ, we believe that we will also live with him. (9) We know that Christ, being raised from the dead, will never die again; death no longer has dominion over him. (10) For the death he died he died to sin, once for all, but the life he lives he lives to God. (11) So you also must consider yourselves dead to sin and alive to God in Christ Jesus. (12) Let not sin therefore reign in your mortal body, to make you obey its passions. (13) Do not present your members to sin as instruments for unrighteousness, but present yourselves to God as those who have been brought from death to life, and your members to God as instruments for righteousness.
So focus on the new life of serving God, and don’t focus on the old carnal ways. Jesus gives us some good advice to help us on the way. He tells us in Luke 9:23-24, to
deny himself and take up his cross daily and follow me. (24) For whoever would save his life will lose it, but whoever loses his life for my sake will save it.
Every day when we wake up, we need to make a conscious decision to take up our cross. What’s a cross used for? Crucifixion. What do we need to crucify? The old man of the flesh. It’s a daily effort. We have to daily live for Jesus and daily make the decision to crucify the flesh.
You also ask if one can ask to be saved. Yes, we can ask to be saved, but God requires certain things of us: belief, repentance, baptism, die to serving sin and live to serve God.
We have an example in Scripture of a man who asked what he needed to do to be saved. This man was a Philippian jailor. We read the account in Acts 16:30-34:
Then he brought them out and said, “Sirs, what must I do to be saved?” (31) And they said, “Believe in the Lord Jesus, and you will be saved, you and your household.” (32) And they spoke the word of the Lord to him and to all who were in his house. (33) And he took them the same hour of the night and washed their wounds; and he was baptized at once, he and all his family. (34) Then he brought them up into his house and set food before them. And he rejoiced along with his entire household that he had believed in God.
Your last question is: How do we get faith?
Faith means belief. If we believe God, we have faith in him. I guess there are various ways to get faith, but basically one would need to check the claims that God makes and if the evidence is there to support those claims, one has a good basis for believing or having faith in God. The apostle Paul tells us in Rom 10:13-15:
For “everyone who calls on the name of the Lord will be saved.” (14) How then will they call on him in whom they have not believed? And how are they to believe in him of whom they have never heard? And how are they to hear without someone preaching? (15) And how are they to preach unless they are sent? As it is written, “How beautiful are the feet of those who preach the good news!”
Paul is describing the crucial importance of preaching the gospel, so people can believe it. People need information and knowledge about God and his purpose so they can weigh up the facts and make a meaningful decision about believing in him or disbelieving.
Paul gives a good succinct answer to your question in Rom 10:17
So faith comes from hearing, and hearing through the word of Christ.