Depending specifically on what you’re talking about, the “means” to God’s grace or forgiveness of sins, is God Himself. God is the actor and we are the recipiants. We have access to the very throne-room of grace by simply going there in prayer freely. His Grace is offered to all because God Himself has offered it.
Grace, or God’s favor is a spiritual favor and our reception of it is firstly spiritual. So God offers this grace to us freely but is not confined or limited by any particular physical or natural “means.” This point is clearly patterned for us over and over again in N.T. scripture.
The concept of quote “a vehicle of grace” is someone’s invention not found or supported in New Testament thinking. If so, please site at least two witnesses.
For example: when Paul said, "For by grace you have been save, through faith, and that not of yourselves… "
Notice how he did not include a natural or physical means to receiving that grace, or, salvation. Why not? It was not in his thinking to do so. When Jesus said, “God so loved the world He gave His only begotten Son that whosoever believes in Him should not parish but have everlasting life,…” Notice in the proclamation He did not include any natural or physical “means” to obtaining it. Again, this point is patterned throughout His teachings on how one receives eternal life.
If He wants to save a soul from hell He will not need water to do it or any other natural means for that matter. Nor does the seeker need another person as a means to help them convert to Christ other than for them to simply preach and communicate the truth of the gospel. Faith comes by hearing and hearing by the word of God.
External, natural, ritualistic, and/or physical means to an end may be found in the O.T. where the people of God were natural people. A natural message using natural means to a natural conclusion was the way God spoke to Israel.
But in the New Testament because we now have become “spiritual” through the indwelling of the Holy Spirit, God’s message to us is primarily spiritual. This is why Jesus said, “… the words that I have spoken to you are SPIRIT and life.” Jn. 6:63.
The new testament is a greater revelation than the old. God no longer speaks to us as natural children using natural means, … but spiritual. I am not restricting God. He can use any means He wants to, but His normal way to convey truth is spiritual, not natural.
Secondly, remember that the Holy Spirit was not resident in the hearts of believes until after the resurrection. Prior to this, all of His disciples were still natural men. This is important when we pick and choose verses of scripture to use in support of our views.