No. The context of this statement is about God’s gifts and calling to Israel. The “gifts” are listed at the beginning of Paul’s discourse in Rom 9:4. They include God’s adoption of Israel as His earthly representatives, His covenant promises, and the giving of the Law. The “calling” is equivalent to God’s election of Israel as His chosen people. Although Israel turned their back on God, the Apostle is describing the faithfulness of God. Some people have extended this description to encompass every gift and calling of God. As believers we must follow the call of God. But nothing here suggests that a person who has once rejected God cannot be saved later. However, there are some situations in which a person is no longer qualified for the kind of spiritual leadership to which God had once called them.
This is the wrong verse for that assertion. It talks about God’s selection of Israel. Joined with the previous verse, the statement is that the Jews are still special to God because of their ancestry and His gifts and callings are without reversal. A call to ministry is not the topic.
Callings vary in form and may change in stages of life. However, obedience to Christ is not negotiable. Paul said that necessity was laid upon him: “Woe is me, if I preach not the gospel.” To reject the call to ministry is to reject Christ’s claim on your life. Love of the world is usually the motive (whether cloaked as family priorities, a preferred occupation, ties to a locale, or mere timidity). When the rich young ruler rejected the call of Christ, he rejected the offer of eternal life. When Demas forsook the ministry, it was evidence that he "loved this present world.” And of course there was Jonah . . . .
I have known people who were fearful about their relationship with God because they had felt a call into Christian service and had not obeyed. Some blundered in marrying a person who hindered their answering the call. Others backslid in willful disobedience, thus turning from the call, but later returned to God. Whether they missed the call through error or through sin, such people can be forgiven. Repentance and confession bring God’s mercy (see I John 1:9 and 2:1-2).
The phrase “without repentance” in this verse does not mean that a person cannot repent over some failure. Rather, it refers to the fact that God will not change (repent) His purposes, plans, and promises for the nation of Israel. Look especially at verses 1-2, 11-12, 23-27, and 30-31 for Paul’s presentation of God’s intention to ultimately save His chosen people. Verse 29 declares that, though His people rebelled, God will still extend grace and mercy to them!
Disobedience to God at any level, including rejecting a call to ministry is sin, which separates us from God.
However, this scripture does not mean that you can’t be forgiven. We are saved by grace through faith in Jesus Christ. In its context this verse has nothing to do with being lost or saved. Does it even refer to a call to ministry? The context is Paul’s discussion of God’s promises to His chosen people, Israel. In verse 1 Paul asks, “Has God rejected His people?” The answer is, “Absolutely not!” The gracious gifts of God and His calling to Israel are irrevocable. God does not go back on His word; that is the point.
Following God is a journey. His leading in life and ministry is often progressive in nature. God’s leading to a particular place or ministry may (or may not) be lifelong. Walking in continued, surrendered obedience should be the “call” of every Christian wherever that leads.
Permit me to do some stirring: In most situations I cannot buy into the "dot command" in that one has ONLY ONE option to do God's will and if that ONLY ONE option is somehow missed, your life is COMPLETELY in ruins. For example, what if my wife of 29 years had married someone else before we had met...then what were my options? Here is where I believe predestination comes into the discussion. Who gave to you your personality-type with its strengths and weaknesses? The source of your gifting is...? Where did your good, wholesome interests originate? Yes, God is the Predestinator of these and He does not change His mind. Whatever you do with these resources, gifts, and abilities MUST be done for God’s honor and glory. To say that one cannot be saved if you don’t obey the call to ministry, well . . . ALL Christians ARE called to ministry . . . even brick layers, carpenters, sales clerks, plumbers, computer technicians, etc. Thus, can a Christian BE a Christian and not minister to people? No.
I see Romans 11:29 within the limited context of God's sovereign purposes for Israel. Therefore, I do not believe that this verse can correctly be applied to an individual's ministry call.
However, persistent and willful disobedience to God’s commands or callings clearly indicates a person's lack of faith (James 2:7-26). Without faith, it is impossible to please God (Hebrews 11:6). It is only through faith that we are saved (Ephesians 2:8). Therefore, I posit that a person cannot stubbornly or ultimately reject God's call to ministry and be assured of their salvation, since "faith without works is dead" (James 2:26).
There are some who reject a call to ministry early in life and then place their faith in Christ years later, often unable to fulfill God's original call to them. To those, I would offer this encouragement: God promises to restore the years that sin has stolen from you (Joel 2:25). Make the most of the rest of your life!