As a dog returneth to his vomit, so a fool returneth to his folly.
The vomit here simply means rejection, a very bad thing that we reject in the process of something, our vomit can be all sorts of things but as a Christian our vomit is sin.
When we give our life to Christ we abstain from sin completely and we turn a new living because been a new Christian the joy and zeal to serve God is there. As times goes on the battle to the promise land become very hard, some survive and some go back to their vomit.
Sin will only destroy us and nothing good will come out of it, instead of running back to our sin we should put faith to God, God will reward us on earth and in heaven, nobody have never regretted working for God.
2 Corinthians 5:17
Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new.
When we genuinely live our life for christ everything becomes new, we can only run from our sin when we live in Christ and sometimes not having full understanding about things of spirit make us lose our way and go back to our vomit, we must trust God and never go back to our sins again. May God help us in Jesus name.
Thanks for your time.